US5942579A - Pouches for packaging flowable materials - Google Patents

Pouches for packaging flowable materials Download PDF

Info

Publication number
US5942579A
US5942579A US09/133,104 US13310498A US5942579A US 5942579 A US5942579 A US 5942579A US 13310498 A US13310498 A US 13310498A US 5942579 A US5942579 A US 5942579A
Authority
US
United States
Prior art keywords
film
percent
seal
ethylene
pouch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US09/133,104
Inventor
Daniel James Falla
Jose V. Saavedra
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dow Chemical Co
Original Assignee
Dow Chemical Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=24154018&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=US5942579(A) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Dow Chemical Co filed Critical Dow Chemical Co
Priority to US09/133,104 priority Critical patent/US5942579A/en
Application granted granted Critical
Publication of US5942579A publication Critical patent/US5942579A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D22/00—Producing hollow articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/08—Copolymers of ethene
    • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
    • C08L23/0815—Copolymers of ethene with aliphatic 1-olefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/41—Opaque
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/71—Resistive to light or to UV
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2439/00—Containers; Receptacles
    • B32B2439/70—Food packaging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D2565/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D2565/38—Packaging materials of special type or form
    • B65D2565/381—Details of packaging materials of special type or form
    • B65D2565/385—Details of packaging materials of special type or form especially suited for or with means facilitating recycling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D75/00—Packages comprising articles or materials partially or wholly enclosed in strips, sheets, blanks, tubes, or webs of flexible sheet material, e.g. in folded wrappers
    • B65D75/008—Standing pouches, i.e. "Standbeutel"
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D75/00—Packages comprising articles or materials partially or wholly enclosed in strips, sheets, blanks, tubes, or webs of flexible sheet material, e.g. in folded wrappers
    • B65D75/40—Packages formed by enclosing successive articles, or increments of material, in webs, e.g. folded or tubular webs, or by subdividing tubes filled with liquid, semi-liquid, or plastic materials
    • B65D75/44—Individual packages cut from webs or tubes
    • B65D75/48—Individual packages cut from webs or tubes containing liquids, semiliquids, or pastes, e.g. cushion-shaped packages
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/08—Copolymers of ethene
    • C08L23/0846—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms
    • C08L23/0853—Vinylacetate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2314/00—Polymer mixtures characterised by way of preparation
    • C08L2314/06—Metallocene or single site catalysts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
    • Y10T428/1334—Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
    • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31855—Of addition polymer from unsaturated monomers
    • Y10T428/31909—Next to second addition polymer from unsaturated monomers
    • Y10T428/31913—Monoolefin polymer

Definitions

  • This invention relates to a pouch used in consumer packaging made from certain film structures useful for packaging flowable materials, for example liquids such as milk.
  • U.S. Pat. Nos. 4,503,102, 4,521,437 and 5,288,531 disclose the preparation of a polyethylene film for use in the manufacture of a disposable pouch for packaging of liquids such as milk.
  • U.S. Pat. No. 4,503,102 discloses pouches made from a blend of a linear ethylene copolymer copolymerized from ethylene and an alpha-olefin at the C 4 to C 10 range and a ethylene-vinyl acetate polymer copolymerized from ethylene and vinyl acetate.
  • the linear polyethylene copolymer has a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.3 to 2.0 g/10 minutes.
  • the ethylene-vinyl acetate polymer has a weight ratio of ethylene to vinyl acetate from 2.2:1 to 24:1 and a melt index of from 0.2 to 10 g/10 minutes.
  • the blend disclosed in U.S. Pat. No. 4,503,102 has a weight ratio of linear low density polyethylene to ethylene-vinyl acetate polymer of from 1.2:1 to 4:1
  • U.S. Pat. No. 4,503,102 also discloses laminates having as a sealant film the aforementioned blend.
  • U.S. Pat. No. 4,521,437 describes pouches made from a sealant film which is from 50 to 100 parts of a linear copolymer of ethylene and octene-1 having a density of from 0.916 to 0.930 g/cm3 and a melt index of 0.3 to 2.0 g/10 minutes and from 0 to 50 parts by weight of at least one polymer selected from the group consisting of a linear copolymer of ethylene and a C 4 -C 10 -alpha-olefin having a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.3 to 2.0 g/10 minutes, a high-pressure polyethylene having a density of from 0.916 to 0.924 g/cm3 and a melt index of from 1 to 10 g/10 minutes and blends thereof.
  • the sealant film disclosed in the U.S. Pat. No. 4,521,437 is selected on the basis of providing (a) pouches with a M-test value substantially smaller, at the same film thickness, than that obtained for pouches made with film of a blend of 85 parts of a linear ethylene/butene-1 copolymer having a density of about 0.919 g/cm3 and a melt index of about 0.75 g/10 minutes and 15 parts of a high pressure polyethylene having a density of about 0.918 g/cm3 and a melt index of 8.5 g/10 minutes, or (b) an M(2)-test value of less than about 12%, for pouches having a volume of from greater than 1.3 to 5 liters, or (c) an M(1.3)-test value of less than about 5% for pouches having a volume of from 0.1 to 1.3 liters.
  • the M, M(2) and M(1.3)tests are defined pouch drop tests in U.S. Pat. No. 4,521,
  • U.S. Pat. No. 5,288,531 discloses pouches made from a film structure having a blend of (a) from 10 to 100 percent by weight of at least one polymeric seal layer of an ultra low density linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C 3 -C 10 with a density of from about 0.89 g/cm3 to less than 0.915 g/cm3 and (b) from 0 to 90 percent by weight of at least one polymer selected from the group consisting of a linear copolymer of ethylene and a C 3 -C 18 -alpha-olefin having a density of greater than 0.916 g/cm3 and a melt index of from 0.1 to 10 g/10 minutes, a high-pressure low density polyethylene having a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.1 to 10 g/10 minutes, or ethylene-vinyl acetate
  • the polyethylene pouches known in the prior art have some deficiencies.
  • the problems associated with films known in the prior art relate to the sealing properties and performance properties of the film for preparing pouches,
  • prior art films made into pouches in general have a high incident of "leakers", i.e., seal defects such as pinholes which develop at or near the seal in which flowable material, for example milk escapes from the pouch.
  • seal defects such as pinholes which develop at or near the seal in which flowable material, for example milk escapes from the pouch.
  • the seal and performance properties of the prior art films have been generally satisfactory, there is still a need in the industry for better seal and performance properties in films for manufacture of hermetically sealed pouches containing flowable materials. More particularly, there is a need for improved sealing properties of the film such as hot tack and melt strength in order to improve the processability of the film and to improve pouches made from the films.
  • the line speed of known packaging equipment used for manufacturing pouches such as form, fill and seal machines, is currently limited by the sealing properties of the film used in the machines.
  • Prior art polyethylene films have low melt strength. Therefore, the speed at which a form, fill and seal machine can produce a pouch is limited and, thus, the number of pouches produced on a form, fill and seal machine is limited. If the melt strength is increased, then the speed of a form, fill and seal machine can be increased and, thus, the number of pouches produced can be increased.
  • One aspect of the present invention provides a pouch containing a flowable material, said pouch being made from a film structure with at least one seal layer of a polymeric composition
  • a polymeric composition comprising: (A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of at least one homogeneously branched substantially linear ethylene/ ⁇ -olefin interpolymer characterized as having: (a) a melt flow ratio, I 10 /I 2 ⁇ 5.63; (b) a molecular weight distribution, Mw/Mn, defined by the equation: Mw/Mn ⁇ (I 10 /I 2 )-4.63, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm3, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using
  • a pouch containing a flowable material said pouch being made from a film structure with at least one seal layer of a polymeric composition
  • a polymeric composition comprising: (A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, a homogeneously branched linear ethylene polymer, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm 3 , a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190° C.; and (B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl a
  • One embodiment of the present invention is a pouch made from a two-layer coextruded film containing an outer layer of substantially linear ethylene polymer or homogeneously branched linear ethylene polymer and an inner seal layer of the aforementioned polymeric composition.
  • Another embodiment of the present invention is a pouch made from a three-layer coextruded film containing an outer layer and a core layer of substantially linear ethylene polymer or homogeneously branched linear ethylene polymer and an inner seal layer of the aforementioned polymeric composition.
  • Another aspect of the present invention is a process for preparing the aforementioned pouch.
  • Yet another embodiment of the present invention is a pouch made from a three-layer coextruded film containing an outer layer and a core layer of ultra low density polyethylene, linear low density polyethylene, high pressure low density polyethylene, and ethylenevinyl acetate copolymer, or a mixture thereof and an inner seal layer of the aforementioned polymeric composition.
  • the film structures for the pouches of the present invention have an improved melt strength and heat seal strength, particularly the end-seal strength.
  • Use of the films for making pouches of the present invention in form, fill and seal machines leads to machine speeds higher than currently obtainable with the use of commercially available film.
  • FIG. 1 shows a perspective view of a pouch package of the present invention.
  • FIG. 2 shows a perspective view of another pouch package of the present invention.
  • FIG. 3 shows a partial, enlarged cross-sectional view of the film structure of a pouch of the present invention.
  • FIG. 4 shows another partial, enlarged cross-sectional view of the film structure of a pouch of the present invention.
  • FIG. 5 shows yet another partial, enlarged cross-sectional view of the film structure of a pouch of the present invention.
  • FIG. 6 is a graphical illustration of end seal strength versus melt strength for blends of AFFINITY PL1880 with high pressure low density polyethylene.
  • the pouch of the present invention for example as shown in FIG. 1 and 2, for packaging flowable materials is manufactured from a three-layer coextruded film structure having a polymeric seal layer comprised of a blend of a substantially linear ethylene polymer or homogeneously branched linear ethylene polymer and a high pressure low density polyethylene having a high melt strength.
  • the blend can also contain an ethylene vinylacetate copolymer, ultra low density polyethylene (“ULDPE”), linear low density polyethylene (“LLDPE”) and high pressure low density polyethylene.
  • Melt strength which is also referred to in the relevant art as “melt tension” is defined and quantified herein to mean the stress or force (as applied by a wind-up drum equipped with a strain cell) required to draw a molten extrudate at some specified rate above its melting point as it passes through the die of a standard plastometer such as the one described in ASTM D1238-E. Melt strength values, which are reported herein in centi-Newtons (cN), are determined using a Gottfert Rheotens at 190° C.
  • melt strength tends to increase with increased molecular weight, or with broadening of the molecular weight distribution and/or with increased melt flow ratios.
  • the melt strength of the high pressure low density polyethylene of the present invention is greater than 10 cN as determined using a Gottfert Rheotens unit at 190° C., preferably from about 13 to 40 cN, and most preferably 15 to 25 cN.
  • the melt strength of the polymeric composition of the present invention is greater than 5 cN as determined using Gottfert Rheotens unit at 190° C., preferably from about 15 to 70 cN, and most preferably 15 to 50.
  • One component of the polymer composition of the present invention is a homogeneously branched ethylene polymer having long chain branching, sometimes referred to as substantially linear ethylene polymer is described in the U.S. Ser. No. 301,948, which description is incorporated herein by reference in its entirety.
  • Preferred ethylene polymers for use in the present invention are those claimed in the U.S. Ser. No. 301,948 and are interpolymers of ethylene with at least one C 3 -C 20 ⁇ -olefins.
  • interpolymer includes copolymer, terpolymer and the like. These ehthylene/ ⁇ -olefin interpolymers preferably have a density, as measured by ASTM D-792, from about 0.85 g/cm3 to about 0.94 g/cm3 and a melt index (I 2 ), as measured according to ASTM D-1238 (condition 190/2.16) from about 0.01 g/10 min. to about 10 g/10 min., and a melt flow ratio (I 10 /I 2 ) from about 5.6 to about 30.
  • Novel ethylene interpolymers can also have a critical shear stress at the onset of gross melt fracture of greater than about 4 ⁇ 10 6 dynes/cm2. However, all of these novel ethylene interpolymers have a critical shear rate, at onset of surface melt fracture, at least 50% greater than the critical shear rate at the onset of surface melt fracture of a linear ethylene polymer having about the same I 2 , Mw/Mn, and density. By the term “about the same” as used herein, is meant that each value is within 10% of the value of the other polymer. These novel ethylene interpolymers also preferably have a molecular weight distribution (Mw/Mn) less than about 3.5, especially from 1.5 to 2.5.
  • Mw/Mn molecular weight distribution
  • homogeneous branching distribution and “homogeneously branched” refer to interpolymers and are defined herein to mean that (1) the ⁇ -olefin monomer is randomly distributed within a given molecule, (2) substantially all of the interpolymer molecules have the same ethylene-to- ⁇ -olefin monomer ratio, (3) the interpolymer is characterized by a narrow short chain branching distribution wherein the composition distribution range index is greater than about 30 percent, preferably greater than about 50 percent, more preferably greater than about 80 percent, most preferably greater than about 9 percent, (4) the interpolymer essentially lacks a measurable high density (crystalline) polymer fraction as measured by known fractionation techniques such as for example, a method that involves polymer fractional elutions as a function of temperature, and (5) the interpolymer is characterized as having substantially reduced levels of n-hexane extractables or substantial amorphism as determined by the FDA test method published as CFR 177.1520(c).
  • the term "homogeneously branched linear ethylene polymer” means that the olefin polymer has a homogeneous short branching distribution but does not have long chain branching. That is, the linear ethylene polymer has an absence of long chain branching.
  • Such polymers include linear low density polyethylene polymers and linear high density polyethylene polymers and can be made using polymerization processes (e.g., as described by Elston in U.S. Pat. No. 3,645,992, the disclosure of which is incorporated herein by reference) which provide uniform branching (i.e., homogeneously branched) distribution.
  • Uniform branching distributions are those in which the comonomer is randomly distributed within a given interpolymer molecule and wherein substantially all of the interpolymer molecules have the same ethylene/comonomer ratio within that interpolymer.
  • Elston uses soluble vanadium catalyst system to make such polymers, however others such as Mitsui Chemical corporation and Exxon Chemical Company have used so-called single site catalyst systems to make polymers having a similar homogeneous structure.
  • the term "homogeneously branched linear ethylene polymer” does not refer to high pressure branched polyethylene which is known to those skilled in the art to have numerous long chain branches.
  • the homogeneously branched linear ethylene polymer is an ethylene/ ⁇ -olefin interpolymer, wherein the ⁇ -olefin is at least one C 3 -C 20 ⁇ -olefin (e.g., 1-propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like), preferably wherein at least one of the ⁇ -olefins is 1-octene.
  • the ethylene/ ⁇ -olefin interpolymer is a copolymer of ethylene and a C 3 -C 20 ⁇ -olefin, especially an ethylene/C 4 -C 6 ⁇ -olefin copolymer.
  • narrow short chain distribution refers to interpolymers and pertains to the distribution of ⁇ -olefin monomer branches of the interpolymer as characterized by its SCBDI (Short Chain Branch Distribution Index) or CDBL (Composition Distribution Branch Index).
  • SCBDI Short Chain Branch Distribution Index
  • CDBL Composition Distribution Branch Index
  • the term is defined herein as greater than about 30 weight percent of the interpolymer molecules have an ⁇ -olefin monomer content within 50 percent of the median total molar ⁇ -olefin monomer content.
  • CDBI of an interpolymer can be readily calculated from data obtained from techniques known in the art, such as for example, temperature rising elution fractionation (abbreviated herein as "TREF") as described, for example, by Wild, et al., Journal of Polymer Science, Poly.
  • TREF temperature rising elution fractionation
  • the preferred TREF techniques does not include purge quantities in CDBI calculations. More preferably, the monomer distribution of the interpolymer and CDBI are determined using 13CNMR analysis in accordance with techniques described in U.S. Pat. No. 5,292,845 and by J. C. Randall in Rev. Macromol. Chem. Phys., C29, pp. 201-317 both disclosures of which are incorporated herein by reference.
  • VLDPE and LLDPE are also well known among practitioners of the linear polyethylene art. See, for example Elston disclosure in U.S. Pat. No. 3,645,992. They can be prepared in solution, slurry or gas phase processes using hafnium, zirconium and vanadium catalyst systems. Ewen, et al. in U.S. Pat. No. 4,937,299 described a method of preparation using metallocene catalysts. The disclosures of Elston and Ewen are incorporated herein by reference.
  • This second class of linear polyethylenes are homogeneously branched polymers, but like the Ziegler-type heterogeneous linear polyethylene, they do not have any long-chain branching. Commercial examples of these polymers are sold by Mitsui Chemical under the designation "TAFMER” and by Exxon Chemical under the designation "EXACT".
  • Heterogeneously branched VLDPE and LLDPE are well known among practitioners of the linear polyethylene art. They are prepared using Ziegler-Natta solution, slurry or gas phase polymerization processes and coordination metal catalysts as described, for example, by Anderson et al. in U.S. Pat. No. 4,076,698, the disclosure of which is incorporated herein by reference. These Ziegler-type linear polyethylenes are not homogeneously branched and they do not have any long-chain branching. Also, these polymers do not show any substantial amorphism at lower densities since they inherently posses a substantial high density (crystalline) polymer fraction. At a density less than 0.90 g/cc, these materials are very difficult to prepare using conventional Ziegler-Natta catalysis and are also very difficult to pelletize. The pellets are tacky and tend to clump together.
  • heterogeneous and heterogeneously branched are used herein in the conventional sense in reference to a linear ethylene interpolymer having a comparatively low short chain branching distribution index.
  • the short chain branching distribution index (SCBDI) is defined as the weight percent of the polymer molecules having a comonomer content within 50 percent of the median total molar comonomer content.
  • the short chain branching distribution index of polyolefins that are crystallizable from solutions can be determined by well-known temperature rising elution fractionation techniques, such as those described by Wild, et al., Journal of Polymer Science, Poly. Phys. Ed., Vol. 20, p. 441 (1982), L. D.
  • ultra low density polyethylene ULDPE
  • very low density polyethylene VLDPE
  • LVLDPE linear very low density polyethylene
  • LLDPE linear low density polyethylene
  • heterogeneously branched linear interpolymers suitable for use in the present invention include ATTANE ULDPE polymers supplied by The Dow Chemical Company and FLEOXMER VLDPE polymers supplied by Union Carbide Corporation.
  • LLDPE linear low density polyethylene
  • DOWLEXTM 2045 Trademark of and commercially available from The Dow Chemical Company.
  • the LLDPE is generally a linear copolymer of ethylene and a minor amount of an ⁇ -olefin having from 3 to about 18 carbon atoms, preferably from 4 to about 10 carbon atoms and most preferably 8 carbon atoms.
  • the LLDPE for the polymeric composition of the present invention has a density of greater than 0.916 g/cm3, more preferably from about 0.916 to about 0.940 g/cm3, most preferably from about 0.918 to about 0.926 g/cm3; generally has a melt index of less than 10 g/10 minutes, preferably from about 0.1 to about 10 g/10 minutes, most preferably from about 0.5 to about 2 g/10 minutes and generally has an I 10 /I 2 ratio of from about 0.1 to about 20, preferably from about 5 to about 20, and most preferably 7 to 20.
  • the LLDPE can be prepared by the continuous, batch or semi-batch solution, slurry or gas phase polymerization of ethylene and one or more optional ⁇ -olefin comonomers in the presence of a Ziegler Natta catalyst, such as by the process disclosed in U.S. Pat. No. 4,076,698 to Anderson et al., incorporated herein by reference.
  • Suitable ⁇ -olefin for the LLDPE of the present invention are represented by the following formula:
  • R is a hydrocarbyl radical having from one to twenty carbon atoms.
  • the interpolymerization process can be a solution, slurry or gas phase technique or combinations thereof.
  • Suitable ⁇ -olefin for use as comonomers include 1-propylene, 1-butene, 1-isobutylene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene and 1-octene, as well as other monomer types such as styrene, halo- or alkyl-substituted styrenes, tetrafluoro-ethylene, vinyl benzocyclobutane, 1,4-hexadiene, 1,7-octadiene, and cycloalkenes, e.g., cyclopentene, cyclohexene and cyclooctene.
  • the ⁇ -olefin will be 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, or mixtures thereof. More preferably, the ⁇ -olefin will be 1-hexene, 1-heptene, 1-octene, or mixtures thereof, as coatings, profiles and films fabricated with the resultant extrusion composition will have especially improved abuse properties where such higher ⁇ -olefins are utilized as comonomers. However, most preferably, the ⁇ -olefin will be 1-octene and the polymerization process will be a continuous solution process.
  • the molecular weight distribution of the ethylene ⁇ -olefin interpolymer compositions and the high pressure ethylene polymer compositions are determined by gel permeation chromatography (GPC) on a Waters 150 high temperature chromatographic unit equipped with differential refractometer and three columns of mixed porosity. The columns are supplied by Polymer Laboratories and are commonly packed with pore sizes of 10 3 , 10 4 , 10 5 and 10 6 ⁇ .
  • the solvent is 1,2,4-trichlorobenzene, from which 0.3 percent by weight solutions of the samples are prepared for injection.
  • the flow rate is 1.0 milliliters/minute, unit operating temperature is 140° C. and the injection size is 100 microliters.
  • the molecular weight determination with respect to the polymer backbone is deduced by using narrow molecular weight distribution polystyrene standard (from Polymer Laboratories) in conjunction with their elution volumes.
  • the equivalent polyethylene molecular weights are determined by using appropriate Mark-Houwink coefficients for polyethylene and polystyrene (as described by Williams and Ward in Journal of Polymer Science, Polymer Letters, Vol. 6, p. 621, 1968) to derive the following equation:
  • the Mw/Mn is preferably about 2 to 7, especially about 4.
  • the high pressure low density polyethylene (“LDPE”) useful for the polymer compositions and blends of this invention is widely known and readily available.
  • the LDPE has a density of about 0.916 g/cm 3 to about 0.930 g/cm 3 , and a melt index from about 0.1 to about 1 g/10 minutes.
  • the LDPE used to form a blend with homogeneously branched substantially linear ethylene/ ⁇ -olefin interpolymer or homogeneously branched linear ethylene polymer for use in the seal layer of this invention has a melt strength of greater than 10 cN as determined using a Gottfert Rheotens unit at 190° C.
  • a further description of the high pressure low density polyethylene is found in Modern Plastics Encyclopedia, Mid-October 1992 Issue, Volume 68, Number 11, pages 61 to 63, which description is incorporated by its entirety by reference.
  • the ethylene-vinyl acetate copolymer (“EVA”) useful for polymer compositions and blends of this invention has a weight ratio of ethylene to vinyl acetate from 2.2:1 to 24:1 and a melt index of from about 0.2 g to about 10 g/10 minutes.
  • EVA ethylene-vinyl acetate copolymer
  • LDPE having high melt strength in a film structure for pouches of the present invention (1) provided a pouch that can be fabricated at a fast rate through a form, fill and seal machine, and (2) provides a pouch package having few leakers, particularly when the pouch of the present invention is compared to pouches made with linear low density polyethylene, low density polyethylene or a combination thereof.
  • the film structure of the pouch of the present invention also includes a multilayer or composite film structure 30, preferably containing the above-described polymer seal layer being the inner layer of the pouch.
  • the multilayer film structure for the pouch of the present invention may contain various combination of film layers as long as the seal layer forms part of the ultimate film structure.
  • the multilayer film structure for the pouch of the present invention may be a coextruded film, a coated film or a laminated film.
  • the film structure also included the seal layer in combination with a barrier film such as polyester, nylon, EVOH, polyvinylidene dichloride (PVDC) such as SARANTM (Trademark of The Dow Chemical Company), metallized films and thin metal foils.
  • PVDC polyvinylidene dichloride
  • SARANTM Trademark of The Dow Chemical Company
  • the end use for the pouch tends to dictate, in a large degree, the selection of the other material or materials used in combination with the seal layer film.
  • the pouches described herein will refer to seal layers used at least on the inside of the pouch.
  • One embodiment of the film structure 30 for the pouch of the present invention comprises seal layer 31 of a blend of a homogeneously branched substantially linear ethylene ⁇ -olefin interpolymer or a homogeneously branched linear ethylene polymer and high melt strength LDPE of this invention and at least one polymeric outer layer 32.
  • the polymeric outer layer 32 is preferably a polyethylene film layer, more preferably a LLDPE.
  • An example of a commercially available LLDPE is DOWLEXTM 2045 (Trademark of the commercially available from The Dow Chemical Company).
  • the thickness of the outer layer 32 may be any thickness so long as the seal layer 31 has a minimum thickness of about 0.1 mil (2.5 microns).
  • FIG. 4 Another embodiment of the film structure 30 for the pouch of the present invention, shown in FIG. 4, comprises the polymeric layer 32 sandwiched between two polymeric seal layers 31.
  • Still another embodiment of the film structure 30 for the pouch of the present invention comprises at least one polymeric core layer 33 between at least one polymeric outer layer 32 and at least one polymeric seal layer 31.
  • the polymeric layer 33 may be the same polymer layer as the outer layer 32 or preferably a different polymer, and more preferably an LDPE, for example DOWLEXTM 2049 (Trademark of and commercially available from The Dow Chemical Company) that has a higher density than the outer layer 32.
  • the thickness of the core layer 33 may be any thickness so long as the seal layer 31 has a minimum thickness of about 0.1 mil (2.5 microns).
  • the ultimate film thickness of the final film product used for making the pouch of the present invention is from about 0.5 mil (12.7 microns) to about 10 mils (254 microns), preferably from about 1 mil (25.4 microns) to about 5 mils (127 microns); more preferably from about 2 mils (50.8 microns) to 4 mils (100 microns).
  • Additives known to those skilled in the art, such as anti-block agents, slip additives, UV stabilizers, pigments and processing aids may he added to the polymers from which the pouches of the present invention are made.
  • the film structure for the pouches of the present invention has design flexibility. Different LDPE polymers can be used in the outer and core layers to optimize specific film properties such as film stiffness. Thus, the film can be optimized for specific applications such as for a vertical form, film and seal machine.
  • the polyethylene film structure used to make a pouch of the present invention is made by either the blown tube extrusion method or the cast extrusion method, methods well known in the art.
  • the blown tube extrusion method is described, for example, in Modern Plastics Mid-October 1989 Encyclopedia Issue, Volume 66, Number 11, pages 264 to 266.
  • the cast extrusion method is described, for example, in Modern Plastics Mid-October 1989 Encyclopedia Issue, Volume 66, Number 11, pages 256 to 257.
  • Embodiments of the pouches of the present invention, shown in FIG. 1 and 2 are hermetically sealed containers filled with "flowable materials".
  • flowable materials it is meant, materials which are flowable under gravity or which may be pumped.
  • flowable materials does not include gaseous materials.
  • the flowable materials include liquids for example milk, water, fruit juice, oil; bodily fluids, chemical reagents and various liquids used for medical treatments and diagnoses emulsions for example ice cream mix, soft margarine; pastes for example meat pates, peanut butter; preservers for example jams, pie fillings marmalade; jellies; doughs; ground meat for example sausage meat; powders for example gelatin powders, detergents; granular solids for example nuts, sugar; and like materials.
  • the pouch of the present invention is particularly useful for liquid foods for example milk.
  • the flowable material may also include oleaginous liquids for example cooking oil or motor oil.
  • FIGS. 1 and 2 are made in so-called form, fill and seal machines well known in the art.
  • a pouch 10 being a tubular member 11 having a longitudinal lap seal 12 and transverse seals 13 such that, a "pillow-shaped" pouch is formed when the pouch is filled with flowable material.
  • a pouch 20 being a tubular member 21 having a peripheral fin seal 22 along three sides of the tubular member 21, that is, the top seal 22a and the longitudinal side seals 22b and 22c, and having a bottom substantially concave or "bowl-shaped” member 23 sealed to the bottom portion of the tubular member 21 such that when viewed in cross-section, longitudinally, substantially a semi-circular or “bowed-shaped” bottom portion is formed when the pouch is filled with flowable material.
  • the pouch shown in FIG. 2 is an example of so-called "Enviro-Pak" pouch known in the art.
  • the pouch manufactured according to the present invention is preferably the pouch shown in FIG. 1 made on so-called vertical form, fill and seal (VFFS) machines well known in the art.
  • VFFS vertical form, fill and seal
  • Examples of commercially available VFFS machines include those manufactured by Hayssen, Thimonnier, Tetra Pak, or Prepac.
  • a VFFS machine is described in the following reference: F. C. Lewis, "Form-Fill-Seal," Packaging Encyclopedia, page 180, 1980.
  • a sheet of the plastic film structure described herein is fed into a VFFS machine where the sheet is formed into a continuous tube in a tube-forming section.
  • the tubular member is formed by sealing the longitudinal edges of the film together--either by lapping the plastic film and sealing the film using an inside/outside seal or by fin sealing the plastic film using an inside/inside seal.
  • a sealing bar seals the tube transversely at one end being the bottom of the "pouch", and then the fill material, for example milk, is added to the "pouch.”
  • the sealing bar then seals the top end of the pouch and either burns through the plastic film or cuts the film, thus, separating the formed completed pouch from the tube.
  • the process of making a pouch with a VFFS machine is generally described in U.S. Pat. Nos. 4,503,102 and 4,521,437 incorporated herein by reference.
  • the capacity of the pouches of the present invention may vary.
  • the pouches may contain from about 5 milliliters to about 10 liters, preferably from about 1 liter to about 8 liters, and more preferably from about 1 milliliter to about 5 liters of flowable material.
  • the film structure for the pouch of the present invention has precisely controlled strength.
  • the use of the film structure described in the present invention for making a pouch results in a stronger pouch, and, therefore, more preferably, the pouch contains fewer use-related leakers.
  • the use of a substantially linear ethylene polymer or homogeneously branched linear ethylene polymer and LDPE blend in the seal layer of the present invention in a two or three-layer coextruded film product will provide a film structure that can be used for making pouches at a faster rate in the VFFS and such pouches produced will contain fewer leakers.
  • the polyethylene pouch of the present invention is a good alternative.
  • the use of the polyethylene pouch for packaging consumer liquids such as milk has its advantages over containers used in the past: the glass bottle, paper carton, and high density polyethylene jug.
  • the previously used containers consumed large amounts of natural resources in their manufacture, required a significant amount of space in landfill, used a large amount of storage space and used more energy in temperature control of the product (due to the heat transfer properties of the container).
  • the polyethylene pouch of the present invention made of thin polyethylene film, used for liquid packaging, offers many advantages over the containers used in the past.
  • the polyethylene pouch (1) consumes less natural resources, (2) requires less space in a landfill, (3) can be recycled, (4) can be processed easily, (5) requires less storage space, (6) uses less energy for storage (heat transfer properties of package), (7) can be safely incinerated and (8) can be reused, for example, the empty pouch can be used for other applications such as freezer bags, sandwich bags, and general purpose storage bags.
  • Erucamide, a slip agent; SiO 2 , an antiblock agent; and a processing aid were added to each of the resins described in Table I such that the final concentrations of the additives were as follows: 1200 ppm erucamide; 2500 ppm SiO 2 .
  • Multilayered blown films were made using the resin blends described in Table III and an Egan 3-layer co-extrusion line.
  • the line was operated at standard extruder conditions with a blow up ratio of 2.0 and melt temperature of 430° F.
  • the 3 layers of the coextruded film consisted of two identical skin layers (A) and a core layer (B) in a A/B/A configuration, having the layer ratio of A:B:A equal to 1:3:1. All layers were formulated to contain the same level of slip, antiblock and processing aid.
  • each of the three layers contained 20% by weight of LDPE as indicated in Table III except Example IB.
  • the film made from the resin blend of Example 1B in Table II comprised of 20% by weight of DOWLEX 2045 and 80% by weight of LDPE 135I in the core layer (B).
  • Film structures produced were subjected to physical testing to determine the various properties thereof including:
  • the hot tack strength of sample films was measured using the "DTC Hot Tack Test Method," which measures the force required to separate a heat seal before the seal has had a chance to fully cool (crystallize). This simulates the filling of material into a pouch before the seal has had a chance to cool.
  • the "DTC Hot Tack Test Method” is a test method using a DTC Hot Tack Tester Model #52D according to the following conditions:
  • the heat seal strength of sample films was measured using the "DTC Heat Seal Strength Test Method," which is designed to measure the force required to separate a seal after the material has cooled to 23° C. temperature.
  • the film samples were exposed to a relative humidity of 50 percent and a temperature of 23° C. for a minimum of 24 hours prior to testing.
  • the "DTC Heat Seal Strength Test Method” uses a DTC Hot Tack Tester Model #52D, wherein the heat seal portion of the tester is used, according to the following conditions:
  • the seal strength of the film samples was determined using an Instron Tensile Tester Model #1122 according to the following test conditions:
  • the present invention is illustrated by the following examples but is not to be limited thereby.
  • the 3-layer coextruded films made from resin blends described in Table III were slit to a width of 15 inches (38.1 cm) to produce 2-liter milk pouches using a Prepac IS6 Vertical, Form, Fill and Seal machine located at a commercial dairy.
  • the unit packaged 2-liter milk filled pouches at the rate of 30 pouches per minute per filling head under normal operating conditions.
  • For each film tested approximately 16-20 milk-filled pouches were collected. They were inspected for initial seal integrity. Ten (10) pouches were drained, washed and dried for further evaluation.
  • the pouches made from multilayer film containing only AFFINITY PL1880 in the seal layer had significant seal thinning and end seal stringers as shown in Table VIII.
  • the pouches made with 20% LDPE 526I had some seal thinning and some end seal stringers film polymer filaments coming from the seal area. No seal thinning or stringers were found with the 20% pouches containing 20% LDPE 135I or LDPE XU 60021.62 in the seal layer of the film.
  • seal strength was found to increase as the melt strength of the polymer blend in the seal layer increased. No correlation was evident between LDPE melt index and seal strength.
  • the pouches made from films containing 20% 135I and XU 60021.62 in the seal layer showed very little seal thinning and no end seal stringers (fine polymer filaments coming from the seal area), while the pouches containing 100% AFFINITY PL1880 had significant seal thinning and stringers.
  • the weakest part of a good seal is typically the film just in front of the seal bead. Any thinning of this film results in lower seal strengths since this is the region that fails when the seal is stressed. Comparing the melt strength of the resin blends (Table II) with the amount of film thinning seen with the pouches made with a commercial VFFS unit (Table X), it is seen that, as the melt strength of the resin blend increased, the amount of film thinning decreased. No correlation was seen between film thinning (Table X) and melt index of LDPE in resin blends (Table I).
  • Table XI shows Hottack data for LDPE 135I, AFFINITY PL1880, and EXACT 3033 as well as predicted and observed hottack values for the blends of 80% by weight of AFFINITY PL1880 or EXACT 3033 and 20% by weight of LDPE 135I. It can be seen that the observed hottack strength of the AFFINITY PL1880 or EXACT 3033 and LDPE 135I blends of the present invention is significantly higher than the predicted level for the blend indicating a clearly synergistic effect.

Abstract

An environmentally friendly polymer film pouch made from a polyethylene film structure for the packaging of flowable materials, for example milk, including, for example, a pouch made from a monolayer or multilayer film structure such as a two-layer or a three-layer coextruded film containing at least one layer of a blend of a substantially linear ethylene polymer or a homogeneously branched ethylene polymer and a high pressure low density polyethylene as a seal layer. Also disclosed is a process for making the pouch for packaging flowable materials using a film structure described hereinabove.

Description

CROSS-REFERENCE TO RELATED APPLICATION
This application is a divisional of copending application Ser. No. 08/540,107 filed Oct. 6, 1995 pending.
BACKGROUND OF THE INVENTION
This invention relates to a pouch used in consumer packaging made from certain film structures useful for packaging flowable materials, for example liquids such as milk.
U.S. Pat. Nos. 4,503,102, 4,521,437 and 5,288,531 disclose the preparation of a polyethylene film for use in the manufacture of a disposable pouch for packaging of liquids such as milk. U.S. Pat. No. 4,503,102 discloses pouches made from a blend of a linear ethylene copolymer copolymerized from ethylene and an alpha-olefin at the C4 to C10 range and a ethylene-vinyl acetate polymer copolymerized from ethylene and vinyl acetate. The linear polyethylene copolymer has a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.3 to 2.0 g/10 minutes. The ethylene-vinyl acetate polymer has a weight ratio of ethylene to vinyl acetate from 2.2:1 to 24:1 and a melt index of from 0.2 to 10 g/10 minutes. The blend disclosed in U.S. Pat. No. 4,503,102 has a weight ratio of linear low density polyethylene to ethylene-vinyl acetate polymer of from 1.2:1 to 4:1 U.S. Pat. No. 4,503,102 also discloses laminates having as a sealant film the aforementioned blend.
U.S. Pat. No. 4,521,437 describes pouches made from a sealant film which is from 50 to 100 parts of a linear copolymer of ethylene and octene-1 having a density of from 0.916 to 0.930 g/cm3 and a melt index of 0.3 to 2.0 g/10 minutes and from 0 to 50 parts by weight of at least one polymer selected from the group consisting of a linear copolymer of ethylene and a C4 -C10 -alpha-olefin having a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.3 to 2.0 g/10 minutes, a high-pressure polyethylene having a density of from 0.916 to 0.924 g/cm3 and a melt index of from 1 to 10 g/10 minutes and blends thereof. The sealant film disclosed in the U.S. Pat. No. 4,521,437 is selected on the basis of providing (a) pouches with a M-test value substantially smaller, at the same film thickness, than that obtained for pouches made with film of a blend of 85 parts of a linear ethylene/butene-1 copolymer having a density of about 0.919 g/cm3 and a melt index of about 0.75 g/10 minutes and 15 parts of a high pressure polyethylene having a density of about 0.918 g/cm3 and a melt index of 8.5 g/10 minutes, or (b) an M(2)-test value of less than about 12%, for pouches having a volume of from greater than 1.3 to 5 liters, or (c) an M(1.3)-test value of less than about 5% for pouches having a volume of from 0.1 to 1.3 liters. The M, M(2) and M(1.3)tests are defined pouch drop tests in U.S. Pat. No. 4,521,437. The pouches may also be made from composite films in which the sealant film forms at least the inner layer.
U.S. Pat. No. 5,288,531 discloses pouches made from a film structure having a blend of (a) from 10 to 100 percent by weight of at least one polymeric seal layer of an ultra low density linear ethylene copolymer interpolymerized from ethylene and at least one alpha-olefin in the range of C3 -C10 with a density of from about 0.89 g/cm3 to less than 0.915 g/cm3 and (b) from 0 to 90 percent by weight of at least one polymer selected from the group consisting of a linear copolymer of ethylene and a C3 -C18 -alpha-olefin having a density of greater than 0.916 g/cm3 and a melt index of from 0.1 to 10 g/10 minutes, a high-pressure low density polyethylene having a density of from 0.916 to 0.930 g/cm3 and a melt index of from 0.1 to 10 g/10 minutes, or ethylene-vinyl acetate copolymer having a weight ratio of ethylene to vinyl acetate from 2.2:1 to 24:1 and a melt index of from 0.2 to 10 g/10 minutes. The heat seal layer in the U.S. Pat. No. 5,288,531 provides improved hot tack strength and lower heat seal initiation temperature to a two-layer or three-layer coextruded multilayer film structure described therein.
The polyethylene pouches known in the prior art have some deficiencies. The problems associated with films known in the prior art relate to the sealing properties and performance properties of the film for preparing pouches, In particular, prior art films made into pouches in general have a high incident of "leakers", i.e., seal defects such as pinholes which develop at or near the seal in which flowable material, for example milk escapes from the pouch. Although the seal and performance properties of the prior art films have been generally satisfactory, there is still a need in the industry for better seal and performance properties in films for manufacture of hermetically sealed pouches containing flowable materials. More particularly, there is a need for improved sealing properties of the film such as hot tack and melt strength in order to improve the processability of the film and to improve pouches made from the films.
For example, the line speed of known packaging equipment used for manufacturing pouches such as form, fill and seal machines, is currently limited by the sealing properties of the film used in the machines. Prior art polyethylene films have low melt strength. Therefore, the speed at which a form, fill and seal machine can produce a pouch is limited and, thus, the number of pouches produced on a form, fill and seal machine is limited. If the melt strength is increased, then the speed of a form, fill and seal machine can be increased and, thus, the number of pouches produced can be increased. Until the present invention, many have attempted to improve sealing properties of the polymeric composition used in pouch film without success.
It is desired to provide a polyethylene film structure for a pouch container having improved melt strength with performance properties as good or better than the known prior art pouch films.
It is also desired to provide a film structure for a pouch container which can be processed through a form fill and seal machine as a monolayer film.
It is further desired to provide a pouch made from the aforementioned film structures such that the pouch has a reduced failure rate.
SUMMARY OF THE INVENTION
One aspect of the present invention provides a pouch containing a flowable material, said pouch being made from a film structure with at least one seal layer of a polymeric composition comprising: (A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of at least one homogeneously branched substantially linear ethylene/α-olefin interpolymer characterized as having: (a) a melt flow ratio, I10 /I2 ≧5.63; (b) a molecular weight distribution, Mw/Mn, defined by the equation: Mw/Mn≦(I10 /I2)-4.63, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm3, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190° C.; and (B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and a homogeneously branched linear ethylene polymer.
Another aspect of the present invention provides a pouch containing a flowable material, said pouch being made from a film structure with at least one seal layer of a polymeric composition comprising: (A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, a homogeneously branched linear ethylene polymer, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm3, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190° C.; and (B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and homogeneously branched substantially linear ethylene/α-olefin interpolymer.
One embodiment of the present invention is a pouch made from a two-layer coextruded film containing an outer layer of substantially linear ethylene polymer or homogeneously branched linear ethylene polymer and an inner seal layer of the aforementioned polymeric composition.
Another embodiment of the present invention is a pouch made from a three-layer coextruded film containing an outer layer and a core layer of substantially linear ethylene polymer or homogeneously branched linear ethylene polymer and an inner seal layer of the aforementioned polymeric composition.
Another aspect of the present invention is a process for preparing the aforementioned pouch.
Yet another embodiment of the present invention is a pouch made from a three-layer coextruded film containing an outer layer and a core layer of ultra low density polyethylene, linear low density polyethylene, high pressure low density polyethylene, and ethylenevinyl acetate copolymer, or a mixture thereof and an inner seal layer of the aforementioned polymeric composition.
It has been discovered that the film structures for the pouches of the present invention have an improved melt strength and heat seal strength, particularly the end-seal strength. Use of the films for making pouches of the present invention in form, fill and seal machines leads to machine speeds higher than currently obtainable with the use of commercially available film.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a perspective view of a pouch package of the present invention.
FIG. 2 shows a perspective view of another pouch package of the present invention.
FIG. 3 shows a partial, enlarged cross-sectional view of the film structure of a pouch of the present invention.
FIG. 4 shows another partial, enlarged cross-sectional view of the film structure of a pouch of the present invention.
FIG. 5 shows yet another partial, enlarged cross-sectional view of the film structure of a pouch of the present invention.
FIG. 6 is a graphical illustration of end seal strength versus melt strength for blends of AFFINITY PL1880 with high pressure low density polyethylene.
DETAILED DESCRIPTION OF THE INVENTION
The pouch of the present invention, for example as shown in FIG. 1 and 2, for packaging flowable materials is manufactured from a three-layer coextruded film structure having a polymeric seal layer comprised of a blend of a substantially linear ethylene polymer or homogeneously branched linear ethylene polymer and a high pressure low density polyethylene having a high melt strength. The blend can also contain an ethylene vinylacetate copolymer, ultra low density polyethylene ("ULDPE"), linear low density polyethylene ("LLDPE") and high pressure low density polyethylene.
"Melt strength" which is also referred to in the relevant art as "melt tension" is defined and quantified herein to mean the stress or force (as applied by a wind-up drum equipped with a strain cell) required to draw a molten extrudate at some specified rate above its melting point as it passes through the die of a standard plastometer such as the one described in ASTM D1238-E. Melt strength values, which are reported herein in centi-Newtons (cN), are determined using a Gottfert Rheotens at 190° C. In general, for ethylene α-olefin interpolymers and high pressure ethylene polymers, melt strength tends to increase with increased molecular weight, or with broadening of the molecular weight distribution and/or with increased melt flow ratios. The melt strength of the high pressure low density polyethylene of the present invention is greater than 10 cN as determined using a Gottfert Rheotens unit at 190° C., preferably from about 13 to 40 cN, and most preferably 15 to 25 cN. Further, the melt strength of the polymeric composition of the present invention is greater than 5 cN as determined using Gottfert Rheotens unit at 190° C., preferably from about 15 to 70 cN, and most preferably 15 to 50.
One component of the polymer composition of the present invention is a homogeneously branched ethylene polymer having long chain branching, sometimes referred to as substantially linear ethylene polymer is described in the U.S. Ser. No. 301,948, which description is incorporated herein by reference in its entirety.
Preferred ethylene polymers for use in the present invention are those claimed in the U.S. Ser. No. 301,948 and are interpolymers of ethylene with at least one C3 -C20 α-olefins.
As used herein, the term "interpolymer" includes copolymer, terpolymer and the like. These ehthylene/α-olefin interpolymers preferably have a density, as measured by ASTM D-792, from about 0.85 g/cm3 to about 0.94 g/cm3 and a melt index (I2), as measured according to ASTM D-1238 (condition 190/2.16) from about 0.01 g/10 min. to about 10 g/10 min., and a melt flow ratio (I10 /I2) from about 5.6 to about 30.
I10 is measured in accordance with ASTM D-1238 (condition 190/10). Novel ethylene interpolymers, depending on their density, can also have a critical shear stress at the onset of gross melt fracture of greater than about 4×106 dynes/cm2. However, all of these novel ethylene interpolymers have a critical shear rate, at onset of surface melt fracture, at least 50% greater than the critical shear rate at the onset of surface melt fracture of a linear ethylene polymer having about the same I2, Mw/Mn, and density. By the term "about the same" as used herein, is meant that each value is within 10% of the value of the other polymer. These novel ethylene interpolymers also preferably have a molecular weight distribution (Mw/Mn) less than about 3.5, especially from 1.5 to 2.5.
The terms "homogeneous branching distribution" and "homogeneously branched" refer to interpolymers and are defined herein to mean that (1) the α-olefin monomer is randomly distributed within a given molecule, (2) substantially all of the interpolymer molecules have the same ethylene-to-α-olefin monomer ratio, (3) the interpolymer is characterized by a narrow short chain branching distribution wherein the composition distribution range index is greater than about 30 percent, preferably greater than about 50 percent, more preferably greater than about 80 percent, most preferably greater than about 9 percent, (4) the interpolymer essentially lacks a measurable high density (crystalline) polymer fraction as measured by known fractionation techniques such as for example, a method that involves polymer fractional elutions as a function of temperature, and (5) the interpolymer is characterized as having substantially reduced levels of n-hexane extractables or substantial amorphism as determined by the FDA test method published as CFR 177.1520(c). By "substantial amorphism", it is meant that greater than 75 weight percent of the whole interpolymer is soluble under prescribed test conditions.
The term "homogeneously branched linear ethylene polymer" means that the olefin polymer has a homogeneous short branching distribution but does not have long chain branching. That is, the linear ethylene polymer has an absence of long chain branching. Such polymers include linear low density polyethylene polymers and linear high density polyethylene polymers and can be made using polymerization processes (e.g., as described by Elston in U.S. Pat. No. 3,645,992, the disclosure of which is incorporated herein by reference) which provide uniform branching (i.e., homogeneously branched) distribution. Uniform branching distributions are those in which the comonomer is randomly distributed within a given interpolymer molecule and wherein substantially all of the interpolymer molecules have the same ethylene/comonomer ratio within that interpolymer. In his polymerization process, Elston uses soluble vanadium catalyst system to make such polymers, however others such as Mitsui Chemical corporation and Exxon Chemical Company have used so-called single site catalyst systems to make polymers having a similar homogeneous structure.
The term "homogeneously branched linear ethylene polymer" does not refer to high pressure branched polyethylene which is known to those skilled in the art to have numerous long chain branches. Typically, the homogeneously branched linear ethylene polymer is an ethylene/α-olefin interpolymer, wherein the ∝-olefin is at least one C3 -C20 α-olefin (e.g., 1-propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like), preferably wherein at least one of the α-olefins is 1-octene. Most preferably, the ethylene/α-olefin interpolymer is a copolymer of ethylene and a C3 -C20 α-olefin, especially an ethylene/C4 -C6 α-olefin copolymer.
The term "narrow short chain distribution" as applied herein refers to interpolymers and pertains to the distribution of α-olefin monomer branches of the interpolymer as characterized by its SCBDI (Short Chain Branch Distribution Index) or CDBL (Composition Distribution Branch Index). The term is defined herein as greater than about 30 weight percent of the interpolymer molecules have an α-olefin monomer content within 50 percent of the median total molar α-olefin monomer content. CDBI of an interpolymer can be readily calculated from data obtained from techniques known in the art, such as for example, temperature rising elution fractionation (abbreviated herein as "TREF") as described, for example, by Wild, et al., Journal of Polymer Science, Poly. Phys Ed., Vol. 20, p. 441 (1982), or in U.S. Pat. No. 4,798,081, both disclosures of which are incorporated herein by reference. However, the preferred TREF techniques does not include purge quantities in CDBI calculations. More preferably, the monomer distribution of the interpolymer and CDBI are determined using 13CNMR analysis in accordance with techniques described in U.S. Pat. No. 5,292,845 and by J. C. Randall in Rev. Macromol. Chem. Phys., C29, pp. 201-317 both disclosures of which are incorporated herein by reference.
Homogeneously branched VLDPE and LLDPE are also well known among practitioners of the linear polyethylene art. See, for example Elston disclosure in U.S. Pat. No. 3,645,992. They can be prepared in solution, slurry or gas phase processes using hafnium, zirconium and vanadium catalyst systems. Ewen, et al. in U.S. Pat. No. 4,937,299 described a method of preparation using metallocene catalysts. The disclosures of Elston and Ewen are incorporated herein by reference. This second class of linear polyethylenes are homogeneously branched polymers, but like the Ziegler-type heterogeneous linear polyethylene, they do not have any long-chain branching. Commercial examples of these polymers are sold by Mitsui Chemical under the designation "TAFMER" and by Exxon Chemical under the designation "EXACT".
Heterogeneously branched VLDPE and LLDPE are well known among practitioners of the linear polyethylene art. They are prepared using Ziegler-Natta solution, slurry or gas phase polymerization processes and coordination metal catalysts as described, for example, by Anderson et al. in U.S. Pat. No. 4,076,698, the disclosure of which is incorporated herein by reference. These Ziegler-type linear polyethylenes are not homogeneously branched and they do not have any long-chain branching. Also, these polymers do not show any substantial amorphism at lower densities since they inherently posses a substantial high density (crystalline) polymer fraction. At a density less than 0.90 g/cc, these materials are very difficult to prepare using conventional Ziegler-Natta catalysis and are also very difficult to pelletize. The pellets are tacky and tend to clump together.
The terms "heterogeneous" and heterogeneously branched" are used herein in the conventional sense in reference to a linear ethylene interpolymer having a comparatively low short chain branching distribution index. The short chain branching distribution index (SCBDI) is defined as the weight percent of the polymer molecules having a comonomer content within 50 percent of the median total molar comonomer content. The short chain branching distribution index of polyolefins that are crystallizable from solutions can be determined by well-known temperature rising elution fractionation techniques, such as those described by Wild, et al., Journal of Polymer Science, Poly. Phys. Ed., Vol. 20, p. 441 (1982), L. D. Cady, "The Role of Comonomer Type and Distribution in LLDPE Product Performance," SPE Regional Technical Conference, Quaker Square Hilton, Akron, Ohio, October 1-2, pp. 107-119 (1985), or U.S. Pat. No. 4,798,081.
The terms "ultra low density polyethylene" (ULDPE), "very low density polyethylene" (VLDPE) and "linear very low density polyethylene" (LVLDPE) have been used interchangeable in the polyethylene art to designate the polymer subset of linear low density polyethylenes having a density about 0.915 g/cc. The term "linear low density polyethylene" (LLDPE) is then applied to those linear polyethylenes having a density above 0.915 g/cc. These terms do not, in themselves, indicate whether the polymer is homogeneously branched or heterogeneously branched.
Commercial examples of heterogeneously branched linear interpolymers suitable for use in the present invention include ATTANE ULDPE polymers supplied by The Dow Chemical Company and FLEOXMER VLDPE polymers supplied by Union Carbide Corporation.
Yet another component of the polymer composition of the present invention is a polyethylene referred to hereinafter as "linear low density polyethylene" ("LLDPE"). An example of a commercially available LLDPE is DOWLEX™ 2045 (Trademark of and commercially available from The Dow Chemical Company). The LLDPE is generally a linear copolymer of ethylene and a minor amount of an α-olefin having from 3 to about 18 carbon atoms, preferably from 4 to about 10 carbon atoms and most preferably 8 carbon atoms. The LLDPE for the polymeric composition of the present invention has a density of greater than 0.916 g/cm3, more preferably from about 0.916 to about 0.940 g/cm3, most preferably from about 0.918 to about 0.926 g/cm3; generally has a melt index of less than 10 g/10 minutes, preferably from about 0.1 to about 10 g/10 minutes, most preferably from about 0.5 to about 2 g/10 minutes and generally has an I10 /I2 ratio of from about 0.1 to about 20, preferably from about 5 to about 20, and most preferably 7 to 20.
The LLDPE can be prepared by the continuous, batch or semi-batch solution, slurry or gas phase polymerization of ethylene and one or more optional α-olefin comonomers in the presence of a Ziegler Natta catalyst, such as by the process disclosed in U.S. Pat. No. 4,076,698 to Anderson et al., incorporated herein by reference.
Suitable α-olefin for the LLDPE of the present invention are represented by the following formula:
CH.sub.2 =CHR
where R is a hydrocarbyl radical having from one to twenty carbon atoms. The interpolymerization process can be a solution, slurry or gas phase technique or combinations thereof. Suitable α-olefin for use as comonomers include 1-propylene, 1-butene, 1-isobutylene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene and 1-octene, as well as other monomer types such as styrene, halo- or alkyl-substituted styrenes, tetrafluoro-ethylene, vinyl benzocyclobutane, 1,4-hexadiene, 1,7-octadiene, and cycloalkenes, e.g., cyclopentene, cyclohexene and cyclooctene. Preferably, the α-olefin will be 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, or mixtures thereof. More preferably, the α-olefin will be 1-hexene, 1-heptene, 1-octene, or mixtures thereof, as coatings, profiles and films fabricated with the resultant extrusion composition will have especially improved abuse properties where such higher α-olefins are utilized as comonomers. However, most preferably, the α-olefin will be 1-octene and the polymerization process will be a continuous solution process.
The molecular weight distribution of the ethylene α-olefin interpolymer compositions and the high pressure ethylene polymer compositions are determined by gel permeation chromatography (GPC) on a Waters 150 high temperature chromatographic unit equipped with differential refractometer and three columns of mixed porosity. The columns are supplied by Polymer Laboratories and are commonly packed with pore sizes of 103, 104, 105 and 106 Å. The solvent is 1,2,4-trichlorobenzene, from which 0.3 percent by weight solutions of the samples are prepared for injection. The flow rate is 1.0 milliliters/minute, unit operating temperature is 140° C. and the injection size is 100 microliters.
The molecular weight determination with respect to the polymer backbone is deduced by using narrow molecular weight distribution polystyrene standard (from Polymer Laboratories) in conjunction with their elution volumes. The equivalent polyethylene molecular weights are determined by using appropriate Mark-Houwink coefficients for polyethylene and polystyrene (as described by Williams and Ward in Journal of Polymer Science, Polymer Letters, Vol. 6, p. 621, 1968) to derive the following equation:
.sup.M polyethylene=a* (.sup.M polystyrene).sup.b .
In this equation, a =0.4316 and b =1.0. Weight average molecular weight, Mw, is calculated in the usual manner according to the following formula: Mw =Σwi ×Mi, where wi and Mi are the weight fraction and molecular weight, respectively, of the ith fraction eluting from the GPC column.
For LLDPE, the Mw/Mn is preferably about 2 to 7, especially about 4.
The high pressure low density polyethylene ("LDPE") useful for the polymer compositions and blends of this invention is widely known and readily available. The LDPE has a density of about 0.916 g/cm3 to about 0.930 g/cm3, and a melt index from about 0.1 to about 1 g/10 minutes. The LDPE used to form a blend with homogeneously branched substantially linear ethylene/α-olefin interpolymer or homogeneously branched linear ethylene polymer for use in the seal layer of this invention has a melt strength of greater than 10 cN as determined using a Gottfert Rheotens unit at 190° C. A further description of the high pressure low density polyethylene is found in Modern Plastics Encyclopedia, Mid-October 1992 Issue, Volume 68, Number 11, pages 61 to 63, which description is incorporated by its entirety by reference.
The ethylene-vinyl acetate copolymer ("EVA") useful for polymer compositions and blends of this invention has a weight ratio of ethylene to vinyl acetate from 2.2:1 to 24:1 and a melt index of from about 0.2 g to about 10 g/10 minutes. A further description of EVA is found in Modern Plastics Encyclopedia, Mid- October 1992 Issue, Volume 68, Number 11, page 66, which description is incorporated by reference in its entirety.
It is believed that the use of LDPE having high melt strength in a film structure for pouches of the present invention (1) provided a pouch that can be fabricated at a fast rate through a form, fill and seal machine, and (2) provides a pouch package having few leakers, particularly when the pouch of the present invention is compared to pouches made with linear low density polyethylene, low density polyethylene or a combination thereof.
With reference to FIGS. 3 to 5, the film structure of the pouch of the present invention also includes a multilayer or composite film structure 30, preferably containing the above-described polymer seal layer being the inner layer of the pouch.
As will be understood by those skilled in the art, the multilayer film structure for the pouch of the present invention may contain various combination of film layers as long as the seal layer forms part of the ultimate film structure. The multilayer film structure for the pouch of the present invention may be a coextruded film, a coated film or a laminated film. The film structure also included the seal layer in combination with a barrier film such as polyester, nylon, EVOH, polyvinylidene dichloride (PVDC) such as SARANTM (Trademark of The Dow Chemical Company), metallized films and thin metal foils. The end use for the pouch tends to dictate, in a large degree, the selection of the other material or materials used in combination with the seal layer film. The pouches described herein will refer to seal layers used at least on the inside of the pouch.
One embodiment of the film structure 30 for the pouch of the present invention, shown in FIG. 3, comprises seal layer 31 of a blend of a homogeneously branched substantially linear ethylene α-olefin interpolymer or a homogeneously branched linear ethylene polymer and high melt strength LDPE of this invention and at least one polymeric outer layer 32. The polymeric outer layer 32 is preferably a polyethylene film layer, more preferably a LLDPE. An example of a commercially available LLDPE is DOWLEX™ 2045 (Trademark of the commercially available from The Dow Chemical Company). The thickness of the outer layer 32 may be any thickness so long as the seal layer 31 has a minimum thickness of about 0.1 mil (2.5 microns).
Another embodiment of the film structure 30 for the pouch of the present invention, shown in FIG. 4, comprises the polymeric layer 32 sandwiched between two polymeric seal layers 31.
Still another embodiment of the film structure 30 for the pouch of the present invention, shown in FIG. 5, comprises at least one polymeric core layer 33 between at least one polymeric outer layer 32 and at least one polymeric seal layer 31. The polymeric layer 33 may be the same polymer layer as the outer layer 32 or preferably a different polymer, and more preferably an LDPE, for example DOWLEX™ 2049 (Trademark of and commercially available from The Dow Chemical Company) that has a higher density than the outer layer 32. The thickness of the core layer 33 may be any thickness so long as the seal layer 31 has a minimum thickness of about 0.1 mil (2.5 microns).
The ultimate film thickness of the final film product used for making the pouch of the present invention is from about 0.5 mil (12.7 microns) to about 10 mils (254 microns), preferably from about 1 mil (25.4 microns) to about 5 mils (127 microns); more preferably from about 2 mils (50.8 microns) to 4 mils (100 microns).
Additives, known to those skilled in the art, such as anti-block agents, slip additives, UV stabilizers, pigments and processing aids may he added to the polymers from which the pouches of the present invention are made.
As can be seen from the different embodiments of the present invention shown in FIG. 3-5, the film structure for the pouches of the present invention has design flexibility. Different LDPE polymers can be used in the outer and core layers to optimize specific film properties such as film stiffness. Thus, the film can be optimized for specific applications such as for a vertical form, film and seal machine.
The polyethylene film structure used to make a pouch of the present invention is made by either the blown tube extrusion method or the cast extrusion method, methods well known in the art. The blown tube extrusion method is described, for example, in Modern Plastics Mid-October 1989 Encyclopedia Issue, Volume 66, Number 11, pages 264 to 266. The cast extrusion method is described, for example, in Modern Plastics Mid-October 1989 Encyclopedia Issue, Volume 66, Number 11, pages 256 to 257.
Embodiments of the pouches of the present invention, shown in FIG. 1 and 2 are hermetically sealed containers filled with "flowable materials". By "flowable materials" it is meant, materials which are flowable under gravity or which may be pumped. The term "flowable materials" does not include gaseous materials. The flowable materials include liquids for example milk, water, fruit juice, oil; bodily fluids, chemical reagents and various liquids used for medical treatments and diagnoses emulsions for example ice cream mix, soft margarine; pastes for example meat pates, peanut butter; preservers for example jams, pie fillings marmalade; jellies; doughs; ground meat for example sausage meat; powders for example gelatin powders, detergents; granular solids for example nuts, sugar; and like materials. The pouch of the present invention is particularly useful for liquid foods for example milk. The flowable material may also include oleaginous liquids for example cooking oil or motor oil.
Once the film structure for the pouch of the present invention is made, the film structure is cut to the desired width for use in conventional pouch-forming machines. The embodiments of the pouch of the present invention shown in FIGS. 1 and 2 are made in so-called form, fill and seal machines well known in the art. With regard to FIG. 1, there is shown a pouch 10 being a tubular member 11 having a longitudinal lap seal 12 and transverse seals 13 such that, a "pillow-shaped" pouch is formed when the pouch is filled with flowable material.
With regard to FIG. 2, there is shown a pouch 20 being a tubular member 21 having a peripheral fin seal 22 along three sides of the tubular member 21, that is, the top seal 22a and the longitudinal side seals 22b and 22c, and having a bottom substantially concave or "bowl-shaped" member 23 sealed to the bottom portion of the tubular member 21 such that when viewed in cross-section, longitudinally, substantially a semi-circular or "bowed-shaped" bottom portion is formed when the pouch is filled with flowable material. The pouch shown in FIG. 2 is an example of so-called "Enviro-Pak" pouch known in the art.
The pouch manufactured according to the present invention is preferably the pouch shown in FIG. 1 made on so-called vertical form, fill and seal (VFFS) machines well known in the art. Examples of commercially available VFFS machines include those manufactured by Hayssen, Thimonnier, Tetra Pak, or Prepac. A VFFS machine is described in the following reference: F. C. Lewis, "Form-Fill-Seal," Packaging Encyclopedia, page 180, 1980.
In a VFFS packaging process, a sheet of the plastic film structure described herein is fed into a VFFS machine where the sheet is formed into a continuous tube in a tube-forming section. The tubular member is formed by sealing the longitudinal edges of the film together--either by lapping the plastic film and sealing the film using an inside/outside seal or by fin sealing the plastic film using an inside/inside seal. Next, a sealing bar seals the tube transversely at one end being the bottom of the "pouch", and then the fill material, for example milk, is added to the "pouch." The sealing bar then seals the top end of the pouch and either burns through the plastic film or cuts the film, thus, separating the formed completed pouch from the tube. The process of making a pouch with a VFFS machine is generally described in U.S. Pat. Nos. 4,503,102 and 4,521,437 incorporated herein by reference.
The capacity of the pouches of the present invention may vary. Generally, the pouches may contain from about 5 milliliters to about 10 liters, preferably from about 1 liter to about 8 liters, and more preferably from about 1 milliliter to about 5 liters of flowable material.
The film structure for the pouch of the present invention has precisely controlled strength. The use of the film structure described in the present invention for making a pouch results in a stronger pouch, and, therefore, more preferably, the pouch contains fewer use-related leakers. The use of a substantially linear ethylene polymer or homogeneously branched linear ethylene polymer and LDPE blend in the seal layer of the present invention in a two or three-layer coextruded film product will provide a film structure that can be used for making pouches at a faster rate in the VFFS and such pouches produced will contain fewer leakers.
With the trend in today's consumer packaging industry moving toward providing the consumer with more environmentally friendly packages, the polyethylene pouch of the present invention is a good alternative. The use of the polyethylene pouch for packaging consumer liquids such as milk has its advantages over containers used in the past: the glass bottle, paper carton, and high density polyethylene jug. The previously used containers consumed large amounts of natural resources in their manufacture, required a significant amount of space in landfill, used a large amount of storage space and used more energy in temperature control of the product (due to the heat transfer properties of the container).
The polyethylene pouch of the present invention made of thin polyethylene film, used for liquid packaging, offers many advantages over the containers used in the past. The polyethylene pouch (1) consumes less natural resources, (2) requires less space in a landfill, (3) can be recycled, (4) can be processed easily, (5) requires less storage space, (6) uses less energy for storage (heat transfer properties of package), (7) can be safely incinerated and (8) can be reused, for example, the empty pouch can be used for other applications such as freezer bags, sandwich bags, and general purpose storage bags.
The polymeric resins described in Table I herein below were used to prepare samples of blown films shown in the Examples and Comparative Examples.
              TABLE I                                                     
______________________________________                                    
Resin Properties                                                          
                       Melt           Melt                                
                       Index,   Density,                                  
                                      Strength,                           
Resin Name Type        dg/min.  g/cc  cN                                  
______________________________________                                    
AFFINITY PL1880                                                           
           SLEP        1.0      0.903  4                                  
DOWLEX 2045                                                               
           LLDPE       1.0      0.920  6                                  
EXACT 3033 POP-terpolymer                                                 
                       1.3      0.902  7                                  
LDPE 135I  LDPE (tube)  0.22    0.923 19                                  
XU60021.62 LDPE        0.5      0.919 25                                  
           (autoclave)                                                    
LDPE 609C  LDPE (tube)  0.88    0.924 10                                  
LDPE 526I  LDPE (tube) 1.0      0.903 12                                  
______________________________________
Erucamide, a slip agent; SiO2, an antiblock agent; and a processing aid were added to each of the resins described in Table I such that the final concentrations of the additives were as follows: 1200 ppm erucamide; 2500 ppm SiO2.
The composition of various LDPE and LLDPE blends and their melt strength is shown in Table II below.
              TABLE II                                                    
______________________________________                                    
Melt Strength of Resin Blends                                             
Blend                         Melt Strength                               
Designation                                                               
         Description (*)      (cN)                                        
______________________________________                                    
 1       DOWLEX 2045          6.4                                         
 2       AFFINITY PL1880      3.9                                         
 3       EXACT 303            7.3                                         
 4       LDPE 526I            12.1                                        
 5       LDPE 135I            19.5                                        
 6       LDPE 609C            12.1                                        
 7       LDPE XU60021.62      24.3                                        
 8       DOWLEX 2045/10% 135I 10.4                                        
 9       DOWLEX 2045/20% 135I 16.0                                        
10       DOWLEX 2045/30% 135I 19.7                                        
11       DOWLEX 2045/10% 609C 9.5                                         
12       DOWLEX 2045/20% 609C 11.7                                        
13       DOWLEX 2045/30% 609C 13.4                                        
14       DOWLEX 2045/10% XU60021.62                                       
                              11.5                                        
15       DOWLEX 2045/20% XU60021.62                                       
                              24.2                                        
16       DOWLEX 2045/30% XU60021.62                                       
                              30.4                                        
17       AFFINITY PL1880/10% 135I                                         
                              6.9                                         
18       AFFINITY PL1880/20% 135I                                         
                              9.4                                         
19       AFFINITY PL1880/30% 135I                                         
                              9.7                                         
20       AFFINITY PL1880/10% 526I                                         
                              4.9                                         
21       AFFINITY PL1880/20% 526I                                         
                              5.8                                         
22       AFFINITY PL1880/30% 526I                                         
                              6.6                                         
23       AFFINITY PL1880/10% XU60021.62                                   
                              8.4                                         
24       AFFINITY PL1880/20% XU60021.62                                   
                              12.3                                        
25       AFFINITY PL1880/30% XU60021.62                                   
                              14.7                                        
26       EXACT 3033/10% 135I  12.6                                        
27       EXACT 3033/20% 135I  17.6                                        
28       EXACT 3033/30% 135I  20.0                                        
29       EXACT 3033/10% 526I  9.7                                         
30       EXACT 3033/20% 526I  15.2                                        
31       EXACT 3033/30% 526I  15.0                                        
32       EXACT 3033/10% XU60021.62                                        
                              15.0                                        
33       EXACT 3033/20% XU60021.62                                        
                              21.7                                        
34       EXACT 3033/30% XU60021.62                                        
                              39.8                                        
______________________________________                                    
 (*) % refers to percent by weight of LDPE in the blend
A 5 kg sample of each blend shown in Table II was processed through a Leistritz twin screw extruder. The melt strength of the blends were determined using a Gottfert Rheotens unit.
              TABLE III                                                   
______________________________________                                    
Resin Blends for Multilayer (A/B/A) Films                                 
for Physical Property Testing                                             
Exam-                                Overall                              
ple                                  Gauge                                
No.   Resin Blend in Layer A                                              
                      Resin Blend in Layer B                              
                                     (Mils)                               
______________________________________                                    
1A    AFFINITY PL1880 +                                                   
                      DOWLEX 2045 +  2.46                                 
      20%(*) LDPE 135I                                                    
                      20% LDPE 135I                                       
1B    AFFINITY PL1880 +                                                   
                      DOWLEX 2045 +  2.49                                 
      20% LDPE 135I   80% LDPE 135I                                       
2     AFFINITY PL1880 +                                                   
                      DOWLEX 2045 +  2.50                                 
      20% LDPE 503I   20% LDPE 503I                                       
3     AFFINITY PL1880 +                                                   
                      DOWLEX 2045 +  2.10                                 
      20% LDPE 526I   20% LDPE 526I                                       
4     AFFINITY PL1880 +                                                   
                      DOWLEX 2045 +  2.50                                 
      20% XU60021.62I 20% XU60021.62                                      
Comp. 100% AFFINITY PL1880                                                
                      100% DOWLEX 2045                                    
                                     2.54                                 
5     EXACT 3033 +    DOWLEX 2045 +  2.55                                 
      20% LDPE 135I   20% LDPE 135I                                       
6     EXACT 3033 +    DOWLEX 2045 +  2.30                                 
      20% LDPE 503I   20% LDPE 503I                                       
7     EXACT 3033 +    DOWLEX 2045 +  2.57                                 
      20% LDPE 526I   20% LDPE 526X                                       
8     EXACT 3033 +    DOWLEX 2045 +  2.45                                 
      20% LDPE XU60021.62                                                 
                      20% XU60021.62                                      
Comp. 100% EXACT 3033 100% DOWLEX 2045                                    
                                     2.58                                 
B                                                                         
______________________________________                                    
 (*)% refers to percent by weight of LDPE in the blend
EXAMPLES 1-8 AND COMPARATIVE EXAMPLE A AND B
Multilayered blown films were made using the resin blends described in Table III and an Egan 3-layer co-extrusion line. The line was operated at standard extruder conditions with a blow up ratio of 2.0 and melt temperature of 430° F. The 3 layers of the coextruded film consisted of two identical skin layers (A) and a core layer (B) in a A/B/A configuration, having the layer ratio of A:B:A equal to 1:3:1. All layers were formulated to contain the same level of slip, antiblock and processing aid. In films containing LDPE, each of the three layers contained 20% by weight of LDPE as indicated in Table III except Example IB. The film made from the resin blend of Example 1B in Table II comprised of 20% by weight of DOWLEX 2045 and 80% by weight of LDPE 135I in the core layer (B).
Film structures produced were subjected to physical testing to determine the various properties thereof including:
(1) Puncture, using method ASTM D3763;
(2) Dart Impact, using ASTM D1709, Method A;
(3) Elmendorf Tear, using ASTM D1922;
(4) Tensiles, using ASTM D882;
(5) 1% and 2% Secant Modulus, using ASTM D882;
(6) Hot Tack Strength, using method described hereinbelow; and
(7) Heat Seal Strength, using method described hereinbelow;
The hot tack strength of sample films was measured using the "DTC Hot Tack Test Method," which measures the force required to separate a heat seal before the seal has had a chance to fully cool (crystallize). This simulates the filling of material into a pouch before the seal has had a chance to cool.
The "DTC Hot Tack Test Method" is a test method using a DTC Hot Tack Tester Model #52D according to the following conditions:
Specimen Width: 25.4 mm
Sealing Time: 0.5 seconds
Sealing Pressure: 0.27 N/mm/mm
Delay Time: 0.5 seconds
Peel Speed: 150 mm/seconds
Number of Samples/Temperature 5
Temperature Increments: 5° C.
Temperature Range: 75° C.-150° C.
The heat seal strength of sample films was measured using the "DTC Heat Seal Strength Test Method," which is designed to measure the force required to separate a seal after the material has cooled to 23° C. temperature. The film samples were exposed to a relative humidity of 50 percent and a temperature of 23° C. for a minimum of 24 hours prior to testing.
The "DTC Heat Seal Strength Test Method" uses a DTC Hot Tack Tester Model #52D, wherein the heat seal portion of the tester is used, according to the following conditions:
Specimen Width: 25.4 mm
Sealing Time: 0.5 seconds
Sealing Pressure: 0.27 N/mm/mm
Number of Samples/Temperature 5
Temperature Increments: 5° C.
Temperature Range: 80° C.-150° C.
The seal strength of the film samples was determined using an Instron Tensile Tester Model #1122 according to the following test conditions:
Direction of Pull: 90° to seal
Crosshead Speed: 500 mm/minute
Full Scale Load: 5 kg
Number of Samples/Threshold: 1 percent of FSL
Break Criterion: 80 percent
Gauge Length: 2.0 inches (50.8 millimeters)
Sample Width: 1.0 inch (25.4 millimeters)
Physical properties of three-layer (A/B/A) films made from the resin blends shown in Table III are reported in Table IV below, and the results of hottack and heat seal strength are reported in Table V and VI, respectively.
                                  TABLE IV                                
__________________________________________________________________________
Physical Properties of Three-layer (A/B/A) Co-extruded Films              
             AFF                                                          
             1880 +                                                       
             20% AFF                                                      
             1351                                                         
                 1880 +                                                   
                     AFF AFF  AFF AFF     EX   EX  EX  EX                 
             (80%                                                         
                 20% 1880 +                                               
                         1880 +                                           
                              1880 +                                      
                                  1880 +                                  
                                      AFFIN-                              
                                          3033 +                          
                                               3033 +                     
                                                   3033                   
                                                       3033 +             
             LDPE                                                         
                 1351                                                     
                     20% 20% XU                                           
                              20% 20% ITY 20% XU                          
                                               20% 20% 20% EX             
Description  in core)                                                     
                 3 MIL                                                    
                     1351                                                 
                         60021.62                                         
                              5031                                        
                                  5261                                    
                                      1880                                
                                          60021.62                        
                                               1351                       
                                                   5031                   
                                                       5261               
                                                           3033           
__________________________________________________________________________
Gauge  mil   2.49                                                         
                 3.18                                                     
                     2.46                                                 
                         2.50 2.50                                        
                                  2.10                                    
                                      2.54                                
                                          2.45 2.55                       
                                                   2.30                   
                                                       2.57               
                                                           2.58           
Elmendorf                                                                 
       g  MD 253 974 654 648  938 663 1,301                               
                                          654  821 587 901 942            
Tear      CD 657 2,067                                                    
                     1,747                                                
                         1,587                                            
                              1,606                                       
                                  1,318                                   
                                      1,593                               
                                          1,600                           
                                               1,888                      
                                                   1,670                  
                                                       1,913              
                                                           1,484          
Dart Impact                                                               
       g     386 585 470 470  433 410 >632                                
                                          503  467 410 574 612            
Puncture                                                                  
Resistance                                                                
       lbf   25.7                                                         
                 49.8                                                     
                     49.8                                                 
                         44.4 39.6                                        
                                  42.3                                    
                                      53.9                                
                                          48.4 42.6                       
                                                   35.6                   
                                                       45.6               
                                                           63.3           
Energy to                                                                 
       ft-lb/                                                             
             64.9                                                         
                 107.0                                                    
                     132.2                                                
                         114.5                                            
                              113.4                                       
                                  140.6                                   
                                      136.6                               
                                          137.5                           
                                               113.4                      
                                                   108.6                  
                                                       122.0              
                                                           166.0          
Break  in3                                                                
Tensile                                                                   
Failure Load                                                              
       lbf                                                                
          MD 10.2                                                         
                 15.4                                                     
                     12.7                                                 
                         10.7 12.7                                        
                                  10.3                                    
                                      12.9                                
                                          13.8 13.9                       
                                                   12.7                   
                                                       13.8               
                                                           14.5           
          CD 11.0                                                         
                 13.8                                                     
                     12.0                                                 
                         12.3 11.6                                        
                                  7.7 13.6                                
                                          12.1 13.2                       
                                                   11.1                   
                                                       12.1               
                                                           13.7           
Tensile Ulti-                                                             
       psi                                                                
          MD 3,919                                                        
                 4,990                                                    
                     5,073                                                
                         4,247                                            
                              5,052                                       
                                  5,103                                   
                                      5,250                               
                                          5,629                           
                                               5,310                      
                                                   5,383                  
                                                       5,374              
                                                           5,585          
mate      CD 4,296                                                        
                 4,524                                                    
                     4,990                                                
                         4,913                                            
                              4,719                                       
                                  4,799                                   
                                      5,479                               
                                          5,040                           
                                               5,271                      
                                                   5,136                  
                                                       4,539              
                                                           5,424          
Elongation                                                                
       %  MD 499 703 652 780  677 709 662 745  731 736 741 726            
          CD 732 732 738 737  739 783 721 763  775 765 741 721            
Toughness                                                                 
       ft.lb                                                              
          MD 1,101                                                        
                 1,425                                                    
                     1,357                                                
                         1,195                                            
                              1,369                                       
                                  1,458                                   
                                      1,244                               
                                          1,665                           
                                               1,574                      
                                                   1,512                  
                                                       1,552              
                                                           1,364          
       in3                                                                
          CD 1,218                                                        
                 1,251                                                    
                     1,323                                                
                         1,324                                            
                              1,291                                       
                                  1,373                                   
                                      1,344                               
                                          1,372                           
                                               1,435                      
                                                   1,388                  
                                                       1,232              
                                                           1,314          
Tensile Yield                                                             
       psi                                                                
          MD 877 1,339                                                    
                     1,432                                                
                         1,092                                            
                              1,363                                       
                                  1,403                                   
                                      1,315                               
                                          1,397                           
                                               1,338                      
                                                   1,313                  
                                                       1,311              
                                                           1,247          
          CD 1,384                                                        
                 1,378                                                    
                     1,423                                                
                         1,429                                            
                              1,393                                       
                                  1,396                                   
                                      1,439                               
                                          1,490                           
                                               1,423                      
                                                   1,454                  
                                                       1,375              
                                                           1,378          
1% Secant                                                                 
       psi                                                                
          MD 25,500                                                       
                 26,000                                                   
                     26,751                                               
                         26,812                                           
                              27,345                                      
                                  25,175                                  
                                      20,930                              
                                          25,791                          
                                               25,232                     
                                                   25,271                 
                                                       25,048             
                                                           24,072         
          CD 30,400                                                       
                 30,300                                                   
                     31,562                                               
                         32,861                                           
                              32,467                                      
                                  27,572                                  
                                      29,143                              
                                          33,209                          
                                               29,713                     
                                                   30,601                 
                                                       27,849             
                                                           28,956         
2% Secant                                                                 
       psi                                                                
          MD 22,100                                                       
                 22,100                                                   
                     22,528                                               
                         22,866                                           
                              22,683                                      
                                  21,428                                  
                                      17,883                              
                                          21,873                          
                                               21,807                     
                                                   21,443                 
                                                       21,447             
                                                           20,651         
          CD 25,200                                                       
                 25,500                                                   
                     25,452                                               
                         27,490                                           
                              26,052                                      
                                  22,596                                  
                                      24,442                              
                                          27,194                          
                                               24,388                     
                                                   24,946                 
                                                       22,941             
                                                           23,711         
__________________________________________________________________________

                                  TABLE V                                 
__________________________________________________________________________
Hottack Strength (N/in) pf Three-layer (A/B/A) Films                      
    AFF 1880 +                                                            
    20% 1351    AFF 1880 +              EX 3033 +                         
    (80% LD in                                                            
          AFF 1880 +                                                      
                20% XU                                                    
                      AFF 1880 +                                          
                            AFF 1880 +                                    
                                  AFFINITY                                
                                        20% XU                            
                                              EX 3033 +                   
                                                    EX 3033 +             
° C.                                                               
    core) 20% 1351                                                        
                60021.62                                                  
                      20% 5031                                            
                            20% 5261                                      
                                  1880  60021.62                          
                                              20% 1351                    
                                                    20%                   
                                                          EX              
__________________________________________________________________________
                                                          3033            
75  0.20  0.32  0.20  0.15  0.21  0.27  0.20  0.16  0.21  0.19            
80  0.32  0.92  0.76  0.44  0.89  0.61  0.17  0.18  0.23  0.18            
85  1.42  2.39  2.29  2.02  1.63  2.78  0.35  0.23  1.07  1.15            
90  2.41  3.00  2.91  2.66  2.84  3.35  1.49  1.31  1.70  3.23            
95  3.62  4.10  3.74  3.40  3.39  3.74  3.96  3.83  3.31  5.51            
100 4.74  4.70  4.56  4.32  3.60  4.74  6.49  6.36  5.02  5.99            
105 5.23  5.33  5.40  4.15  4.20  4.54  7.87  6.86  5.18  7.08            
110 4.11  4.40  4.33  4.02  4.24  4.38  7.83  6.83  5.21  6.71            
115 3.52  3.70  3.93  3.62  3.78  3.95  7.32  6.25  4.58  6.18            
120 2.91  3.10  3.42  2.93  3.40  3.46  6.16  5.87  3.62  5.50            
125 2.73  2.80  2.98  2.91  2.89  2.82  5.21  4.97  3.35  5.09            
130 2.56  2.36  2.81  2.70  2.68  2.58  4.54  4.30  3.26  4.68            
135 2.39  2.39  2.73  2.62  2.38  2.74  3.85  3.73  2.95  4.35            
140 2.21  2.28  2.51  2.32  2.23  2.85  3.53  3.40  2.51  4.24            
145 1.90  2.06  2.26  2.24  2.08  2.71  2.70  3.03  2.42  3.96            
150 1.83  1.72  2.19  2.20  1.97  2.42  2.65  2.65  2.30  3.68            
__________________________________________________________________________

                                  TABLE VI                                
__________________________________________________________________________
Heat Seal Strength (lb/in) of Three-layer (A/B/A) Films                   
   AFF 1880 +                                                             
   20% 1351    AFF 1880 +        AFFIN-   EX 3033 +                       
   (80% LD in                                                             
         AFF 1880 +                                                       
               20% XU                                                     
                     AFF 1880 +                                           
                           AFF 1880 +                                     
                                 ITY ATTANE                               
                                          20% XU                          
                                                EX 3033                   
                                                      EX 3033             
                                                            EX            
° C.                                                               
   core) 20% 1351                                                         
               60021.62                                                   
                     20% 5031                                             
                           20% 5261                                       
                                 1880                                     
                                     4203 60021.62                        
                                                20% 1351                  
                                                      20%                 
                                                            3033          
__________________________________________________________________________
80 0.31  0.19  0.31  0.20  0.22  0.29                                     
                                     0.38                                 
85 2.60  2.68  1.72  0.97  0.86  2.76                                     
                                     0.39 0.36  0.08  0.05  0.20          
90 3.52  3.79  3.45  3.79  2.93  3.59                                     
                                     1.40 1.40  1.74  1.78  3.02          
95 4.36  4.43  4.01  4.32  3.50  3.87                                     
                                     3.38 3.88  4.27  3.68  3.92          
100                                                                       
   6.43  5.31  4.84  4.60  4.04  4.39                                     
                                     3.75 4.98  5.20  4.43  4.62          
105                                                                       
   7.15  5.51  5.63  4.62  4.60  4.57                                     
                                     3.85 5.83  5.55  5.23  4.92          
110                                                                       
   7.69  5.69  5.62  4.71  4.66  4.68                                     
                                     4.19 5.82  6.05  5.32  4.95          
115                                                                       
   7.30  5.67  5.56  4.90  4.58  4.72                                     
                                     4.51 5.80  6.16  5.33  5.04          
120      5.56  5.74  5.16  4.92  4.88                                     
                                     5.33 5.95  6.16  5.59  4.96          
125                                                                       
   7.60  5.31  5.97  5.23  5.10  4.99                                     
                                     5.27 6.01  6.28  5.33  4.98          
130                                                                       
   8.23  5.89  5.92  5.04  5.05  5.05                                     
                                     5.24 6.38  6.37  4.99  4.95          
135                                                                       
   8.34  5.48  5.93  5.19  5.24  5.20                                     
                                     5.35 6.15  6.28  5.58  5.00          
140                                                                       
   8.77  5.46  5.91  4.94  5.36  5.57                                     
                                     5.42 5.95  6.39  5.43  5.30          
145                                                                       
   8.52  5.43  5.87  4.95  5.50  5.60                                     
                                     5.67 6.04  6.51  5.56  4.98          
150                                                                       
   8.86  5.52  5.70  4.93  5.20  5.40                                     
                                     5.73 6.53  6.58  5.70  5.13          
__________________________________________________________________________
The present invention is illustrated by the following examples but is not to be limited thereby.
EXAMPLES 9-13 AND CONPARATIVE EXAMPLE C
The 3-layer coextruded films made from resin blends described in Table III were slit to a width of 15 inches (38.1 cm) to produce 2-liter milk pouches using a Prepac IS6 Vertical, Form, Fill and Seal machine located at a commercial dairy. The unit packaged 2-liter milk filled pouches at the rate of 30 pouches per minute per filling head under normal operating conditions. For each film tested, approximately 16-20 milk-filled pouches were collected. They were inspected for initial seal integrity. Ten (10) pouches were drained, washed and dried for further evaluation.
The initial examination of end seal integrity involved three steps:
i) Determination Of On-Line Leakers
ii) Subjective Seal Strength Test
iii) Visual Examination of End Seals
On Line Leakers
On line leakers were only seen with the pouches made from 100% AFFINITY PL1880. No leakers were seen with the other films.
Subjective Seal Strength Test
The subjective seal strength test involved squeezing the pouch from one end until the pouch either yielded or the seal failed. Table VII shows that no seal failures were seen with the pouches made with films containing 20% by weight of 135I or XU 60021.62.
Visual Examination of End Seals
The pouches made from multilayer film containing only AFFINITY PL1880 in the seal layer had significant seal thinning and end seal stringers as shown in Table VIII. The pouches made with 20% LDPE 526I had some seal thinning and some end seal stringers film polymer filaments coming from the seal area. No seal thinning or stringers were found with the 20% pouches containing 20% LDPE 135I or LDPE XU 60021.62 in the seal layer of the film.
End Seal Strength
2-liter milk pouches were tested for end seal strength using an Instron Tensile Tester Model # 1122, under same conditions described in connection with the determination of heat seal strength hereinabove.
The seal strengths are shown in Table IX. Seal strength was found to increase as the melt strength of the polymer blend in the seal layer increased. No correlation was evident between LDPE melt index and seal strength.
Microscopy Examination of End Seals
The stringer regions and edge regions of the pouches were cryo-sectioned and examined using light microscopy techniques. Table X summarizes the results.
The pouches made from films containing 20% 135I and XU 60021.62 in the seal layer showed very little seal thinning and no end seal stringers (fine polymer filaments coming from the seal area), while the pouches containing 100% AFFINITY PL1880 had significant seal thinning and stringers.
Seal Region Film Thinning
The weakest part of a good seal is typically the film just in front of the seal bead. Any thinning of this film results in lower seal strengths since this is the region that fails when the seal is stressed. Comparing the melt strength of the resin blends (Table II) with the amount of film thinning seen with the pouches made with a commercial VFFS unit (Table X), it is seen that, as the melt strength of the resin blend increased, the amount of film thinning decreased. No correlation was seen between film thinning (Table X) and melt index of LDPE in resin blends (Table I).
              TABLE VII                                                   
______________________________________                                    
Commercial Dairy Prepac VFFS Evaluation                                   
Subjective Seal Strengths                                                 
                            %     # Pouches                               
                                         # Seal                           
Run #  LLDPE        LDPE    LDPE  Tested Failure                          
______________________________________                                    
Compar-                                                                   
       AFFINITY PL1880       0    7      2                                
ative C                                                                   
 9     AFFINITY PL1880                                                    
                    526I    20    7      1                                
10     AFFINITY PL1880                                                    
                    135I    20    7      0                                
11     AFFINITY PL1880                                                    
                    XU.62   20    7      0                                
12     AFFINITY PL1880                                                    
                    135I    20    8      0                                
       3 mil                                                              
13     AFFINITY PL1880                                                    
                    135I    20    7      0                                
       80% LDPE in core                                                   
______________________________________                                    

              TABLE VIII                                                  
______________________________________                                    
Commercial Dairy Prepac VFFS Evaluation                                   
Visual Examination of End Seals                                           
                                    Visual                                
                              %     Examination                           
Run #    LLDPE        LDPE    LDPE  of Seal                               
______________________________________                                    
Comparative C                                                             
         AFFINITY PL1880                                                  
                      --       0    heavy stringers,                      
                                    seal thinning                         
 9       AFFINITY PL1880                                                  
                      526I    20    some stringers,                       
                                    seal thinning                         
10       AFFINITY PL1880                                                  
                      135I    20    no stringers                          
11       AFFINITY PL1880                                                  
                      XU.62   20    no stringers                          
12       AFFINITY PL1880                                                  
                      135I    20    no stringers                          
         3-mil                                                            
13       AFFINITY PL1880                                                  
                      135I    20    no stringers                          
         80% LDPE in core                                                 
______________________________________                                    

              TABLE IX                                                    
______________________________________                                    
Prepac VFFS                                                               
Pouch End Seal Strength                                                   
                                      Seal                                
                       LDPE     %     Strength,                           
Run #    LLDPE MI      MI       LDPE  lb/in                               
______________________________________                                    
Comparative C                                                             
         AFFINITY PL1880                                                  
                       --        0    5.76                                
 9       AFFINITY PL1880                                                  
                       526I     20    6.25                                
10       AFFINITY PL1880                                                  
                       135I     20    6.78                                
11       AFFINITY PL1880                                                  
                       XU.62    20    6.80                                
12       AFFINITY PL1880                                                  
                       135I     20    7.73                                
         3 MIL                                                            
13       AFFINITY PL1880                                                  
                       135I     20    8.66                                
         80% LDPE IN CORE                                                 
______________________________________                                    

              TABLE X                                                     
______________________________________                                    
Prepac                                                                    
VFFS Microscopy Analysis Summary                                          
                                  **Film                                  
                                  Thick-                                  
                            *Film ness  Reduction                         
                            Thick-                                        
                                  Before                                  
                                        in Film                           
                            ness  Seal, Thickness,                        
#      Description                                                        
                 Comments   μm μm %                                 
______________________________________                                    
Compar-                                                                   
       AFFINITY  severe     69.1  45.9  33                                
ative C                                                                   
       PL1880    thinning and                                             
                 drawing of                                               
                 seal area many                                           
                 seal stringers                                           
 9     AFFINITY  severe     71.8  51.9  28                                
       PL1880 +  thinning, many                                           
       20% LDPE  stingers                                                 
       526I                                                               
10     AFFINITY  good, no   68.7  64.8   6                                
       PL1880 +  thinning, no                                             
       20% LDPE  stringers                                                
       135I                                                               
11     AFFINITY  good, no   80.1  75.0   6                                
       PL1880 +  thinning, no                                             
       20% XU    stringers                                                
       60021.62                                                           
12     AFFINITY  good, no   70.5  69.1   2                                
       PL1880 +  thinning, no                                             
       20% 135I ˜                                                   
                 stringers                                                
       3 MIL                                                              
13     AFFINITY  good, no   67.2  65.6   2                                
       PL1880 +  thinning, no                                             
       20% 135I -                                                         
                 stringers                                                
       80% LDPE                                                           
       in core                                                            
______________________________________                                    
 *measured 550 μm from seal                                            
 **measured cross section at thinnest part of film before the seal
Table XI shows Hottack data for LDPE 135I, AFFINITY PL1880, and EXACT 3033 as well as predicted and observed hottack values for the blends of 80% by weight of AFFINITY PL1880 or EXACT 3033 and 20% by weight of LDPE 135I. It can be seen that the observed hottack strength of the AFFINITY PL1880 or EXACT 3033 and LDPE 135I blends of the present invention is significantly higher than the predicted level for the blend indicating a clearly synergistic effect.
                                  TABLE XI                                
__________________________________________________________________________
Hottack Strength - Affinity                                               
Predicted vs. Observed Values                                             
                 80% AFFINITY                                             
                         AFFINITY                                         
                               80%                                        
   N/IN          PL1880 +                                                 
                         PL1880 +                                         
                               EXACT 3033 +                               
                                       EXACT 3033 +                       
   AFFINITY                                                               
         EXACT                                                            
             LDPE                                                         
                 20% 135I -                                               
                         135I  20% 135I                                   
                                       20% 135I -                         
° C.                                                               
   PL1880                                                                 
         3033                                                             
             135I                                                         
                 PREDICTED                                                
                         OBSERVED                                         
                               PREDICTED                                  
                                       OBSERVED                           
__________________________________________________________________________
 95                                                                       
   3.74  5.51                                                             
             0.18                                                         
                 3.05    4.10  4.48    3.83                               
100                                                                       
   4.76  5.99                                                             
             0.22                                                         
                 3.89    4.70  4.88    6.36                               
105                                                                       
   4.54  7.08                                                             
             0.56                                                         
                 3.78    5.33  5.84    6.86                               
110                                                                       
   4.38  6.71                                                             
             0.81                                                         
                 3.70    4.40  5.59    6.83                               
115                                                                       
   3.95  6.18                                                             
             0.86                                                         
                 3.36    3.70  5.16    6.25                               
120                                                                       
   3.46  5.50                                                             
             0.74                                                         
                 2.94    3.10  4.59    5.87                               
125                                                                       
   2.82  5.09                                                             
             0.69                                                         
                 2.41    2.80  4.21    4.97                               
130                                                                       
   2.58  4.68                                                             
             0.69                                                         
                 2.22    2.36  3.88    4.30                               
135                                                                       
   2.74  4.34                                                             
             0.64                                                         
                 2.34    2.39  3.60    3.73                               
__________________________________________________________________________
Predicted hottack strength was calculated as per the following:
(0.8× AFFINITY PL1880 hottack)+(0.2× LDPE hottack); or
(0.8× EXACT 3033 hottack)+(0.2× LDPE hottack)

Claims (10)

What is claimed is:
1. A film structure of a polymeric composition for a packaging application comprising:
(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of at least one homogeneously branched substantially linear ethylene/∝-olefin interpolymer characterized as having:
(a) a melt flow ratio, I10 /I2 ≧5.63;
(b) a molecular weight distribution, Mw/Mn, defined by the equation: Mw/Mn≦(I10 /I2)-4.63, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm3, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190° C.; and
(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and a homogeneously branched linear ethylene polymer.
2. The film of claim 1 wherein the density of the linear ethylene copolymer is from 0.916 to 0.940 g/cm3.
3. The film of claim 1 wherein the concentration of ethylene vinyl acetate copolymer is 5 to 85 percent based on the total weight of said composition.
4. The film of claim 1 wherein the concentration of ethylene vinyl acetate copolymer is 5 to 25 percent based on the total weight of said composition.
5. The film of claim 1 wherein the melt strength of the polymeric composition is in the range from 5 to 70 cN.
6. A film structure of a polymeric composition for a packaging application comprising:
(A) from 10 to 100 percent, based on the total weight of said composition, of a mixture of (1) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, homogeneously branched linear ethylene polymer, and (2) from 5 to 95 percent by weight, based on 100 weight parts of said mixture, of high pressure low density polyethylene having a density from 0.916 to 0.930 g/cm3, a melt index of less than 1 g/10 minutes and melt strength greater than 10 cN as determined using a Gottfert Rheotens unit at 190° C.; and
(B) from 0 to 90 percent, based on the total weight of said composition, at least one polymer selected from the group consisting of an ultra low density polyethylene, a linear low density polyethylene, a high pressure low density polyethylene, an ethylene-vinyl acetate copolymer, and homogeneously branched substantially linear ethylene/α-olefin interpolymer.
7. The film of claim 6 wherein the density of the linear ethylene copolymer is from 0.916 to 0.940 g/cm3.
8. The film of claim 6 wherein the concentration of ethylene vinyl acetate copolymer is 5 to 85 percent based on the total weight of said composition.
9. The film of claim 6 wherein the concentration of ethylene vinyl acetate copolymer is 5 to 25 percent based on the total weight of said composition.
10. The film of claim 6 wherein the melt strength of the polymeric composition is in the range from 5 to 70 cN.
US09/133,104 1995-10-06 1998-08-12 Pouches for packaging flowable materials Expired - Lifetime US5942579A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US09/133,104 US5942579A (en) 1995-10-06 1998-08-12 Pouches for packaging flowable materials

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08/540,107 US5879768A (en) 1995-10-06 1995-10-06 Pouches for packaging flowable materials
US09/133,104 US5942579A (en) 1995-10-06 1998-08-12 Pouches for packaging flowable materials

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US08/540,107 Division US5879768A (en) 1995-10-06 1995-10-06 Pouches for packaging flowable materials

Publications (1)

Publication Number Publication Date
US5942579A true US5942579A (en) 1999-08-24

Family

ID=24154018

Family Applications (2)

Application Number Title Priority Date Filing Date
US08/540,107 Expired - Lifetime US5879768A (en) 1995-10-06 1995-10-06 Pouches for packaging flowable materials
US09/133,104 Expired - Lifetime US5942579A (en) 1995-10-06 1998-08-12 Pouches for packaging flowable materials

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US08/540,107 Expired - Lifetime US5879768A (en) 1995-10-06 1995-10-06 Pouches for packaging flowable materials

Country Status (15)

Country Link
US (2) US5879768A (en)
EP (1) EP0866744B2 (en)
JP (1) JP3950479B2 (en)
KR (1) KR100494039B1 (en)
CN (1) CN1066099C (en)
AR (1) AR003803A1 (en)
AU (1) AU704902B2 (en)
BR (1) BR9611161A (en)
CA (1) CA2231449C (en)
DE (1) DE69634445T3 (en)
ES (1) ES2239340T5 (en)
MY (1) MY115053A (en)
TW (1) TW343177B (en)
WO (1) WO1997012755A1 (en)
ZA (1) ZA968384B (en)

Cited By (45)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1216824A1 (en) * 2000-12-18 2002-06-26 Mitsui Chemicals, Inc. Sealant for polypropylene and easily openable hermetically sealed package including the same
WO2003040008A2 (en) * 2001-11-06 2003-05-15 Cryovac, Inc. Irradiated multilayer film having seal layer containing hyperbranched polymer
WO2003039958A2 (en) * 2001-11-06 2003-05-15 Cryovac, Inc. Packaging article having heat seal layer containing blend of hyperbranched and semicrystalline olefin polymers
USH2073H1 (en) * 2000-06-19 2003-07-01 Exxon Chemical Patents Inc. Defect propagation resistant stretch films
US6737130B2 (en) 2001-11-06 2004-05-18 Cryovac, Inc. Hermetically heat-sealable, pressure-reclosable packaging article containing substantially spherical homogeneous polyolefin
US6812289B2 (en) 1996-12-12 2004-11-02 Dow Global Technologies Inc. Cast stretch film of interpolymer compositions
US20050003125A1 (en) * 2003-07-01 2005-01-06 Barber Victor Jason Thermoplastic structures for the storing and transporting of organoleptic sensitive products
US20050100754A1 (en) * 2003-08-25 2005-05-12 Moncla Brad M. Aqueous dispersion, its production method, and its use
US20050271888A1 (en) * 2003-08-25 2005-12-08 Dow Global Technologies Inc. Aqueous polymer dispersions and products from those dispersions
US20060024519A1 (en) * 2004-07-30 2006-02-02 Tosoh Corporation Laminate
US20060046048A1 (en) * 2003-02-04 2006-03-02 Mridula Kapur Film layers made from polymer blends
US20060083875A1 (en) * 2004-10-15 2006-04-20 Sonoco Development, Inc., A Corporation Of South Carolina Lap sealable laminate for retort pouch
US20060177650A1 (en) * 2005-02-08 2006-08-10 Toray Plastics (America), Inc. Sealable biaxially oriented polypropylene film for packaging
US20070093603A1 (en) * 2003-06-10 2007-04-26 Wooster Jeffrey J Film layers made from ethylene polymer blends
US20070172685A1 (en) * 2004-03-19 2007-07-26 Mridula Kapur Film layers made from polymer formulations
US20070243331A1 (en) * 2006-02-17 2007-10-18 Dow Global Technologies Inc. Heat sealable compositions from aqueous dispersions
US20070269623A1 (en) * 2006-04-26 2007-11-22 Breck Alan K Flex crack resistant low density polyethylene films
US20080090062A1 (en) * 2006-09-05 2008-04-17 Breck Alan K Polyethylene and polypropylene blends for liquid packaging films
US20080248228A1 (en) * 2007-04-04 2008-10-09 Nova Chemicals (International) S.A. Produce packaging
US20100137501A1 (en) * 2003-08-25 2010-06-03 Moncla Brad M Aqueous dispersion, its production method, and its use
US7731689B2 (en) 2007-02-15 2010-06-08 Baxter International Inc. Dialysis system having inductive heating
US7744554B2 (en) 2002-12-31 2010-06-29 Baxter International Inc. Cassette alignment and integrity testing for dialysis systems
US20110171481A1 (en) * 2003-08-25 2011-07-14 Dow Global Technologies Llc Coating composition and articles made therefrom
US7998115B2 (en) 2007-02-15 2011-08-16 Baxter International Inc. Dialysis system having optical flowrate detection
WO2011117757A2 (en) 2010-03-24 2011-09-29 Cryovac, Inc. Ovenable cook-in film with reduced protein adhesion
WO2012115998A1 (en) 2011-02-23 2012-08-30 Cryovac, Inc. Ovenable cook-in film providing decreased protein adhesion
US8323231B2 (en) 2000-02-10 2012-12-04 Baxter International, Inc. Method and apparatus for monitoring and controlling peritoneal dialysis therapy
US8357749B2 (en) 2003-08-25 2013-01-22 Dow Global Technologies Llc Coating composition and articles made therefrom
US8361023B2 (en) 2007-02-15 2013-01-29 Baxter International Inc. Dialysis system with efficient battery back-up
US8545435B2 (en) 2002-01-03 2013-10-01 Baxter International, Inc. Method and apparatus for providing medical treatment therapy based on calculated demand
US8558964B2 (en) 2007-02-15 2013-10-15 Baxter International Inc. Dialysis system having display with electromagnetic compliance (“EMC”) seal
US8722787B2 (en) 2003-08-25 2014-05-13 Dow Global Technologies Llc Coating composition and articles made therefrom
US8779053B2 (en) 2003-08-25 2014-07-15 Dow Global Technologies Llc Coating compositions
US8870812B2 (en) 2007-02-15 2014-10-28 Baxter International Inc. Dialysis system having video display with ambient light adjustment
US8946329B2 (en) 2003-08-25 2015-02-03 Dow Global Technologies Llc Coating compositions
US8978346B2 (en) 2010-04-16 2015-03-17 Liqui-Box Corporation Multi-layer, ethylene polymer-based films with high-density polyethylene based stiffening layer
US9169406B2 (en) 2003-08-25 2015-10-27 Dow Global Technologies Llc Coating compositions
US9283736B2 (en) 2010-04-16 2016-03-15 Liqui-Box Corporation Multi-layer, ethylene polymer-based films with novel polypropylene blend-based stiffening layer
US9422444B2 (en) 2012-12-28 2016-08-23 Dow Global Technologies Llc Coating compositions
US9533477B2 (en) 2010-04-16 2017-01-03 Liqui-Box Corporation Multi-layer, ethylene polymer-based films with polypropylene-based stiffening layer
US9938413B2 (en) 2012-12-28 2018-04-10 Dow Global Technologies Llc Coating composition and articles made therefrom
WO2019025979A1 (en) 2017-07-31 2019-02-07 Liquibox Spain Sl Machine and process for preparing sterilized flexible-bags for packaging products
WO2019055371A1 (en) 2017-09-13 2019-03-21 Liqui-Box Corporation Process for preventing organoleptic degradation in flexibly-packaged sensitive foods and packaged products thereof
WO2019099348A2 (en) 2017-11-14 2019-05-23 Liqui-Box Corporation Flex-crack resistant and thermally resistant aseptic bulk bags for flexible packaging
US11179516B2 (en) 2017-06-22 2021-11-23 Baxter International Inc. Systems and methods for incorporating patient pressure into medical fluid delivery

Families Citing this family (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU741160B2 (en) * 1997-04-11 2001-11-22 Dow Chemical Company, The Pinhole-resistant extrusion composition, method and article
DE19806475A1 (en) * 1998-02-17 1999-08-19 Wolff Walsrode Ag Multi-layer sealing layer and hermetically sealable packaging material made with it
KR100352785B1 (en) * 1998-03-10 2002-09-16 미쓰이 가가쿠 가부시키가이샤 Ethylene copolymer composition and use thereof
GB9818869D0 (en) * 1998-08-29 1998-10-21 Rexam Med Packaging Ltd Polymeric films and packages produced therefrom
CA2288684A1 (en) * 1999-03-10 2000-09-10 Mitsui Chemicals, Incorporated Uses of ethylene/.alpha.-olefin copolymer and uses of ethylene copolymer composition
US6548572B1 (en) 1999-12-07 2003-04-15 Dupont Canada Inc. Surface printing inks and coatings for use
US6743523B1 (en) 2000-03-16 2004-06-01 Baxter International Inc. Multiple layer film of a new non-PVC material
US6479137B1 (en) 2000-05-09 2002-11-12 Exxon Mobil Oil Corporation Controlled directional tear laminates
US6482532B1 (en) 2000-06-07 2002-11-19 Dow Global Technologies Inc. Easy tear non-halogenic food wrap
SE0100858D0 (en) * 2001-03-12 2001-03-12 Tetra Laval Holdings & Finance Packaging laminate, method of producing a packaging container and the packaging container
AU2003269970A1 (en) * 2002-09-05 2004-03-29 Exxonmobil Chemical Patents Inc. Shrink film
BRPI0314479B1 (en) * 2002-09-23 2015-10-13 Dow Global Technologies Inc polymer composition, skin layer, manufactured article and film
NZ539232A (en) * 2002-09-26 2007-06-29 Marko I R D C Inc Elastomeric film with anti-skid particles suitable as wrapping material
US7947776B2 (en) 2003-08-25 2011-05-24 Dow Global Technologies Llc Aqueous dispersion, its production method, and its use
CN1845952B (en) * 2003-09-05 2010-10-13 陶氏环球技术公司 Improved resin compositions for extrusion coating
TWM249912U (en) * 2004-02-18 2004-11-11 Camry Packing Ind Ltd A valve of air packing bag
AU2006220811A1 (en) * 2005-03-04 2006-09-14 Dow Global Technologies Inc. Improved polyethylene resin compositions having low mi and high melt strength
US20060228503A1 (en) * 2005-04-12 2006-10-12 Marvin Havens Film for chub packaging
CN102020056B (en) * 2009-09-21 2012-11-07 刘建林 Multilayer coextruded liquid packaging film capable of reducing leakage rate
FR2952041B1 (en) * 2009-10-29 2012-02-03 Sartorius Stedim Biotech Sa SOLDERED POCKET WALL MULTILAYER FILM FOR BIOPHARMACEUTICAL PRODUCT.
CN103112158B (en) * 2013-01-31 2016-01-20 石家庄中汇药品包装有限公司 A kind of preparation method of low n-hexane stripping polyethylene film
US9211987B2 (en) 2013-02-20 2015-12-15 Dow Global Technologies Llc Flexible pouch and dock system
USD770915S1 (en) 2013-02-20 2016-11-08 Dow Global Technologies Llc Flexible pouch and dock system
WO2014190039A1 (en) * 2013-05-22 2014-11-27 Dow Global Technologies Llc Low density ethylene-based compositions with improved melt strength, output, and mechanical properties
US10568807B2 (en) * 2014-07-31 2020-02-25 W. L. Gore & Associates, Inc. Storage bag
ES2822291T3 (en) * 2015-05-07 2021-04-30 Borealis Ag Polymeric compositions for extrusion coating
CN105196576A (en) * 2015-09-02 2015-12-30 铜陵翔宇商贸有限公司 Preparing method for cold draw imbalance double-spacing directional linear film packaging bag
US10308736B2 (en) 2015-09-17 2019-06-04 Exxonmobil Chemical Patents Inc. Polyethylene polymers and articles made therefrom
CN106218159B (en) * 2016-07-19 2018-05-22 杭州德雅包装有限公司 Packaging material made of a kind of heat shrink films and the heat shrink films
US20210009794A1 (en) * 2018-03-09 2021-01-14 Prime Polymer Co., Ltd. Resin composition for sealant, multilayer film for sealant, heat-fusible laminated film, and package
KR102130819B1 (en) 2019-12-31 2020-07-06 주식회사 엔베코코스메틱 Method for manufacturing pouch

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0057238A1 (en) * 1980-08-07 1982-08-11 Mitsui Petrochemical Industries, Ltd. Ethylene-alpha-olefin copolymer composition
US4503102A (en) * 1982-01-20 1985-03-05 Du Pont Of Canada, Inc. Pouches of ethylene-α-olefin copolymer/ethylene-vinyl acetate copolymer blends
US4521437A (en) * 1982-06-02 1985-06-04 Du Pont Canada Inc. Pouches of ethylene/octene-1 copolymer film containing a flowable material
WO1993003093A1 (en) * 1991-07-18 1993-02-18 Exxon Chemical Patents Inc. Heat sealed article
US5288531A (en) * 1991-08-09 1994-02-22 The Dow Chemical Company Pouch for packaging flowable materials
WO1994006857A1 (en) * 1992-09-16 1994-03-31 Exxon Chemical Patents Inc. Soft films having enhanced physical properties
US5360648A (en) * 1993-06-24 1994-11-01 The Dow Chemical Company Pouch for packaging flowable materials

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2643348B2 (en) † 1988-09-01 1997-08-20 三井石油化学工業株式会社 Polyethylene resin composition and film
US5395471A (en) † 1991-10-15 1995-03-07 The Dow Chemical Company High drawdown extrusion process with greater resistance to draw resonance
EP0600482B1 (en) * 1992-12-03 1998-04-08 Mitsubishi Chemical Corporation Resin composition for laminates
GB9321254D0 (en) * 1993-10-14 1993-12-01 Du Pont Canada Pouches of ethylene copolymer film containing a flowable material
GB9402430D0 (en) * 1994-02-08 1994-03-30 Du Pont Canada Multilayer ethylene copolymer film
IL115911A0 (en) † 1994-11-14 1996-01-31 Dow Chemical Co Extrusion compositions having high drawdown and substantially reduced neck-in

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0057238A1 (en) * 1980-08-07 1982-08-11 Mitsui Petrochemical Industries, Ltd. Ethylene-alpha-olefin copolymer composition
US4503102A (en) * 1982-01-20 1985-03-05 Du Pont Of Canada, Inc. Pouches of ethylene-α-olefin copolymer/ethylene-vinyl acetate copolymer blends
US4521437A (en) * 1982-06-02 1985-06-04 Du Pont Canada Inc. Pouches of ethylene/octene-1 copolymer film containing a flowable material
WO1993003093A1 (en) * 1991-07-18 1993-02-18 Exxon Chemical Patents Inc. Heat sealed article
US5288531A (en) * 1991-08-09 1994-02-22 The Dow Chemical Company Pouch for packaging flowable materials
US5364486A (en) * 1991-08-09 1994-11-15 The Dow Chemical Company Pouch for packaging flowable materials
WO1994006857A1 (en) * 1992-09-16 1994-03-31 Exxon Chemical Patents Inc. Soft films having enhanced physical properties
US5360648A (en) * 1993-06-24 1994-11-01 The Dow Chemical Company Pouch for packaging flowable materials

Cited By (90)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6812289B2 (en) 1996-12-12 2004-11-02 Dow Global Technologies Inc. Cast stretch film of interpolymer compositions
US10322224B2 (en) 2000-02-10 2019-06-18 Baxter International Inc. Apparatus and method for monitoring and controlling a peritoneal dialysis therapy
US8323231B2 (en) 2000-02-10 2012-12-04 Baxter International, Inc. Method and apparatus for monitoring and controlling peritoneal dialysis therapy
US9474842B2 (en) 2000-02-10 2016-10-25 Baxter International Inc. Method and apparatus for monitoring and controlling peritoneal dialysis therapy
USH2073H1 (en) * 2000-06-19 2003-07-01 Exxon Chemical Patents Inc. Defect propagation resistant stretch films
EP1216824A1 (en) * 2000-12-18 2002-06-26 Mitsui Chemicals, Inc. Sealant for polypropylene and easily openable hermetically sealed package including the same
US6933346B2 (en) * 2000-12-18 2005-08-23 Mitsui Chemicals, Inc. Sealant for polypropylene and easily openable hermetically sealed package including the same
US6858275B2 (en) 2001-11-06 2005-02-22 Cryovac, Inc. Irradiated multilayer film having seal layer containing hyperbranched polymer
WO2003040008A3 (en) * 2001-11-06 2003-08-28 Cryovac Inc Irradiated multilayer film having seal layer containing hyperbranched polymer
US6761965B2 (en) 2001-11-06 2004-07-13 Cryovac, Inc. Irradiated multilayer film having seal layer containing hyperbranched polymer
US6733851B2 (en) 2001-11-06 2004-05-11 Cryovac, Inc. Packaging article having heat seal layer containing blend of hyperbranched and semicrystalline olefin polymers
WO2003040008A2 (en) * 2001-11-06 2003-05-15 Cryovac, Inc. Irradiated multilayer film having seal layer containing hyperbranched polymer
US20040013896A1 (en) * 2001-11-06 2004-01-22 Isabella Ferri Irradiated multilayer film having seal layer containing hyperbranched polymer
WO2003039958A2 (en) * 2001-11-06 2003-05-15 Cryovac, Inc. Packaging article having heat seal layer containing blend of hyperbranched and semicrystalline olefin polymers
WO2003039958A3 (en) * 2001-11-06 2003-09-25 Cryovac Inc Packaging article having heat seal layer containing blend of hyperbranched and semicrystalline olefin polymers
US6737130B2 (en) 2001-11-06 2004-05-18 Cryovac, Inc. Hermetically heat-sealable, pressure-reclosable packaging article containing substantially spherical homogeneous polyolefin
US8545435B2 (en) 2002-01-03 2013-10-01 Baxter International, Inc. Method and apparatus for providing medical treatment therapy based on calculated demand
US7744554B2 (en) 2002-12-31 2010-06-29 Baxter International Inc. Cassette alignment and integrity testing for dialysis systems
US8206338B2 (en) 2002-12-31 2012-06-26 Baxter International Inc. Pumping systems for cassette-based dialysis
US20060046048A1 (en) * 2003-02-04 2006-03-02 Mridula Kapur Film layers made from polymer blends
US7659343B2 (en) 2003-06-10 2010-02-09 Dow Global Technologies, Inc. Film layers made from ethylene polymer blends
US20070093603A1 (en) * 2003-06-10 2007-04-26 Wooster Jeffrey J Film layers made from ethylene polymer blends
US7041352B2 (en) * 2003-07-01 2006-05-09 Pechiney Emballage Flexible Europe Thermoplastic structures for the storing and transporting of organoleptic sensitive products
US20060177616A1 (en) * 2003-07-01 2006-08-10 Barber Victor J Thermoplastic structures for the storing and transporting of organoleptic sensitive products
US20050003125A1 (en) * 2003-07-01 2005-01-06 Barber Victor Jason Thermoplastic structures for the storing and transporting of organoleptic sensitive products
US9416291B2 (en) 2003-08-25 2016-08-16 Dow Global Technologies Llc Coating compositions
US7803865B2 (en) 2003-08-25 2010-09-28 Dow Global Technologies Inc. Aqueous dispersion, its production method, and its use
US20050100754A1 (en) * 2003-08-25 2005-05-12 Moncla Brad M. Aqueous dispersion, its production method, and its use
US9169406B2 (en) 2003-08-25 2015-10-27 Dow Global Technologies Llc Coating compositions
US8946329B2 (en) 2003-08-25 2015-02-03 Dow Global Technologies Llc Coating compositions
US8349929B2 (en) 2003-08-25 2013-01-08 Dow Global Technologies Llc Coating composition and articles made therefrom
US8193275B2 (en) 2003-08-25 2012-06-05 Dow Global Technologies Llc Aqueous dispersion, its production method, and its use
US20100048784A1 (en) * 2003-08-25 2010-02-25 Dow Global Technologies Inc. Aqueous dispersion, its production method, and its use
US8809448B2 (en) 2003-08-25 2014-08-19 Dow Global Technologies Llc Aqueous polymer dispersions and products from those dispersions
US20100137501A1 (en) * 2003-08-25 2010-06-03 Moncla Brad M Aqueous dispersion, its production method, and its use
US8779053B2 (en) 2003-08-25 2014-07-15 Dow Global Technologies Llc Coating compositions
US8163837B2 (en) 2003-08-25 2012-04-24 Dow Global Technologies Llc Aqueous polymer dispersions and products from those dispersions
US7763676B2 (en) 2003-08-25 2010-07-27 Dow Global Technologies Inc. Aqueous polymer dispersions and products from those dispersions
US8158711B2 (en) 2003-08-25 2012-04-17 Dow Global Technologies Llc Aqueous dispersion, its production method, and its use
US20100247920A1 (en) * 2003-08-25 2010-09-30 Dow Global Technologies Inc. Aqueous polymer dispersions and products from those dispersions
US8722787B2 (en) 2003-08-25 2014-05-13 Dow Global Technologies Llc Coating composition and articles made therefrom
US8618210B2 (en) 2003-08-25 2013-12-31 Dow Global Technologies, Llc Aqueous polymer dispersions and products from those dispersions
US7935755B2 (en) 2003-08-25 2011-05-03 Dow Global Technologies Llc Aqueous polymer dispersions and products from those dispersions
US20110171481A1 (en) * 2003-08-25 2011-07-14 Dow Global Technologies Llc Coating composition and articles made therefrom
US20050271888A1 (en) * 2003-08-25 2005-12-08 Dow Global Technologies Inc. Aqueous polymer dispersions and products from those dispersions
US8357749B2 (en) 2003-08-25 2013-01-22 Dow Global Technologies Llc Coating composition and articles made therefrom
US8063128B2 (en) 2003-08-25 2011-11-22 Dow Global Technologies Llc Aqueous dispersion, its production method, and its use
US8076421B2 (en) 2004-03-19 2011-12-13 Dow Global Technologies Llc Film layers made from polymer formulations
US20070172685A1 (en) * 2004-03-19 2007-07-26 Mridula Kapur Film layers made from polymer formulations
US20060024519A1 (en) * 2004-07-30 2006-02-02 Tosoh Corporation Laminate
EP1629973A1 (en) * 2004-07-30 2006-03-01 Tosoh Corporation Laminate
US7544422B2 (en) 2004-07-30 2009-06-09 Tosoh Corporation Laminate
US20060083875A1 (en) * 2004-10-15 2006-04-20 Sonoco Development, Inc., A Corporation Of South Carolina Lap sealable laminate for retort pouch
US20060177650A1 (en) * 2005-02-08 2006-08-10 Toray Plastics (America), Inc. Sealable biaxially oriented polypropylene film for packaging
US7722794B2 (en) 2005-02-08 2010-05-25 Toray Plastics (America), Inc. Method for producing a sealable biaxially oriented polypropylene film for packaging
WO2006085887A1 (en) * 2005-02-08 2006-08-17 Toray Plastics (America), Inc. Sealable biaxially oriented polypropylene film for packaging
US20070243331A1 (en) * 2006-02-17 2007-10-18 Dow Global Technologies Inc. Heat sealable compositions from aqueous dispersions
US20070269623A1 (en) * 2006-04-26 2007-11-22 Breck Alan K Flex crack resistant low density polyethylene films
US8252397B2 (en) 2006-04-26 2012-08-28 Liqui-Box Corporation Flex crack resistant low density polyethylene films
US8561379B2 (en) 2006-04-26 2013-10-22 Liqui-Box Corporation Process for making pouches from flex-crack-resistant, LDPE films
US8211533B2 (en) 2006-09-05 2012-07-03 Liqui-Box Corporation Resin blend of ethylene alpha olefin interpolymer and heterogeneous interpolymer for liquid packaging films
US8196373B2 (en) 2006-09-05 2012-06-12 Liqui-Box Corporation Pouch making process including use of liquid packaging films of polyethylene and polypropylene blends
US20080090062A1 (en) * 2006-09-05 2008-04-17 Breck Alan K Polyethylene and polypropylene blends for liquid packaging films
US8563102B2 (en) 2006-09-05 2013-10-22 Liqui-Box Corporation Resin blend of ethylene alpha olefin interpolymer and heterogeneous interpolymer for liquid packaging films
US20110033644A1 (en) * 2006-09-05 2011-02-10 Liqui-Box Corporation Polyethylene And Polypropylene Blends For Liquid Packaging Films
US20110033135A1 (en) * 2006-09-05 2011-02-10 Liqui-Box Corporation Polyethylene And Polypropylene Blends For Liquid Packaging Films
US8361023B2 (en) 2007-02-15 2013-01-29 Baxter International Inc. Dialysis system with efficient battery back-up
US7731689B2 (en) 2007-02-15 2010-06-08 Baxter International Inc. Dialysis system having inductive heating
US8870812B2 (en) 2007-02-15 2014-10-28 Baxter International Inc. Dialysis system having video display with ambient light adjustment
US9799274B2 (en) 2007-02-15 2017-10-24 Baxter International Inc. Method of controlling medical fluid therapy machine brightness
US8558964B2 (en) 2007-02-15 2013-10-15 Baxter International Inc. Dialysis system having display with electromagnetic compliance (“EMC”) seal
US7998115B2 (en) 2007-02-15 2011-08-16 Baxter International Inc. Dialysis system having optical flowrate detection
US20080248228A1 (en) * 2007-04-04 2008-10-09 Nova Chemicals (International) S.A. Produce packaging
WO2011117757A2 (en) 2010-03-24 2011-09-29 Cryovac, Inc. Ovenable cook-in film with reduced protein adhesion
US9283736B2 (en) 2010-04-16 2016-03-15 Liqui-Box Corporation Multi-layer, ethylene polymer-based films with novel polypropylene blend-based stiffening layer
US8978346B2 (en) 2010-04-16 2015-03-17 Liqui-Box Corporation Multi-layer, ethylene polymer-based films with high-density polyethylene based stiffening layer
US9533477B2 (en) 2010-04-16 2017-01-03 Liqui-Box Corporation Multi-layer, ethylene polymer-based films with polypropylene-based stiffening layer
US20170136745A1 (en) * 2010-04-16 2017-05-18 Liqui-Box Corporation Multi-Layer Ethylene Polymer-Based Films With Polypropylene-Based Stiffening Layer
US9757926B2 (en) * 2010-04-16 2017-09-12 Liqui-Box Corporation Multi-layer ethylene polymer-based films with polypropylene-based stiffening layer
WO2012115998A1 (en) 2011-02-23 2012-08-30 Cryovac, Inc. Ovenable cook-in film providing decreased protein adhesion
US9938413B2 (en) 2012-12-28 2018-04-10 Dow Global Technologies Llc Coating composition and articles made therefrom
US9422444B2 (en) 2012-12-28 2016-08-23 Dow Global Technologies Llc Coating compositions
US11179516B2 (en) 2017-06-22 2021-11-23 Baxter International Inc. Systems and methods for incorporating patient pressure into medical fluid delivery
WO2019025979A1 (en) 2017-07-31 2019-02-07 Liquibox Spain Sl Machine and process for preparing sterilized flexible-bags for packaging products
WO2019055371A1 (en) 2017-09-13 2019-03-21 Liqui-Box Corporation Process for preventing organoleptic degradation in flexibly-packaged sensitive foods and packaged products thereof
US11383910B2 (en) 2017-09-13 2022-07-12 Liqui-Box Corporation Process for preventing organoleptic degradation in flexibly-packaged sensitive foods and packaged products thereof
US11878854B2 (en) 2017-09-13 2024-01-23 Liqui-Box Corporation Process for preventing organoleptic degradation in flexibly-packaged sensitive foods and packaged products thereof
WO2019099348A2 (en) 2017-11-14 2019-05-23 Liqui-Box Corporation Flex-crack resistant and thermally resistant aseptic bulk bags for flexible packaging
US10960649B2 (en) 2017-11-14 2021-03-30 Liqui-Box Corporation Flex-crack resistant and thermally resistant aseptic bulk bags for flexible packaging
US11254109B2 (en) 2017-11-14 2022-02-22 Liqui-Box Corporation Flex-crack resistant and thermally resistant aseptic bulk bags for flexible packaging

Also Published As

Publication number Publication date
DE69634445D1 (en) 2005-04-14
EP0866744A4 (en) 1999-09-15
AU704902B2 (en) 1999-05-06
US5879768A (en) 1999-03-09
JP3950479B2 (en) 2007-08-01
EP0866744A1 (en) 1998-09-30
CA2231449A1 (en) 1997-04-10
EP0866744B1 (en) 2005-03-09
AU7251396A (en) 1997-04-28
BR9611161A (en) 1999-03-30
JPH11513345A (en) 1999-11-16
DE69634445T3 (en) 2009-06-04
KR100494039B1 (en) 2005-10-28
EP0866744B2 (en) 2008-09-10
CN1066099C (en) 2001-05-23
DE69634445T2 (en) 2006-01-05
ZA968384B (en) 1998-04-06
CN1198706A (en) 1998-11-11
MY115053A (en) 2003-03-31
AR003803A1 (en) 1998-09-09
KR19990064043A (en) 1999-07-26
ES2239340T3 (en) 2005-09-16
CA2231449C (en) 2004-09-21
ES2239340T5 (en) 2009-03-16
WO1997012755A1 (en) 1997-04-10
TW343177B (en) 1998-10-21

Similar Documents

Publication Publication Date Title
US5942579A (en) Pouches for packaging flowable materials
US5721025A (en) Pouches for packaging flowable materials in pouches
US6117465A (en) Pouches for packaging flowable materials
CA2165340C (en) Pouch for packaging flowable materials
EP0743902B1 (en) Multilayer ethylene copolymer film
NZ243873A (en) Film structure comprising at least one copolymer of ethylene and at least one alphaolefin; pouch containing fluid material (such as milk)
AU742162B2 (en) Pouches for packaging flowable materials
WO1999006476A1 (en) Pouch for packaging flowable materials
EP0948432A1 (en) Films having improved sealing properties
NZ336920A (en) Pouches for packaging flowable materials with polymeric composition comprising 5-95% ethylene copolymer and C3-C18 alpha olefin
MXPA98004440A (en) Novedos bags to pack fluible materials in bol
MXPA99007377A (en) Pouches for packaging flowable materials
KR20000070945A (en) Pouches For Packaging flowable Materials
NO326217B1 (en) A bag containing a flowing material, a process for its preparation, and a film composition of a polymer blend for a packaging application.

Legal Events

Date Code Title Description
STCF Information on status: patent grant

Free format text: PATENTED CASE

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FPAY Fee payment

Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

FPAY Fee payment

Year of fee payment: 12